hi3520dv200: add hifb-demo package with MPP bootstrap port

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Summary

• Ports the minimum subset of upstream Hisilicon mpp/sample/common/sample_comm_sys.c + sample_comm_vo.c (via Mihawk086/HI3520DVR) needed to bring up MPP SYS + VO on hi3520dv200's V2.0.5.1 SDK so /dev/fb0 becomes openable from userspace.
• Adds hifb_demo — a standalone test program that exercises the hifb ioctls (FBIOPUT_ALPHA_HIFB, FBIOPUT_SCREEN_ORIGIN_HIFB, FBIOPUT_SHOW_HIFB), mmaps /dev/fb0 (1280×720 RGB565, the HD layer the vendor load_hisilicon script provisions with vram0_size=8100 KB), and draws SMPTE-style color bars plus an animated rectangle at ~30 fps as a visible self-check.
• Enables the package in hi3520dv200_lite_defconfig so CI builds the binary.

Why

After #2104 (CONFIG_FB=y) the hifb.ko symbol-resolution errors are gone, but on the current openipc hi3520dv200 build there is no resident MPP daemon and the hifb driver's fb_open callback still returns EPERM because no VO video layer has been attached. The bootstrap port in this PR is what unblocks /dev/fb0 (and proves the path end-to-end).

The key bring-up call sequence (in trimmed SAMPLE_COMM_SYS_Init)

HI_MPI_SYS_Exit
HI_MPI_VB_DestroyPool(0..VB_MAX_POOLS)
HI_MPI_VB_Exit
HI_MPI_VB_SetConf
HI_MPI_VB_Init
HI_MPI_SYS_SetConf(u32AlignWidth=16)   ← the critical missing call
HI_MPI_SYS_Init

Without HI_MPI_SYS_SetConf, HI_MPI_SYS_Init returns 0xa0028010 = HI_ERR_SYS_NOTREADY on V2.0.5.1.

What's deliberately not ported

• HDMI helpers (SAMPLE_COMM_VO_HdmiStart and friends) — hi3520dv200 libmpi.so ships no HI_MPI_HDMI_* exports, so they can't link. HDMI is brought up implicitly when VO_INTF_HDMI is selected in VO_PUB_ATTR_S.
• Writeback / Snap / Channel / Vpss-bind helpers — not needed for fb-only and pull in newer-SDK types (VO_WBC, VO_WBC_SOURCE_S, COMPRESS_MODE_E) that V2.0.5.1 doesn't define.
• HI_MPI_VB_ExitModCommPool loop — symbol added in a later SDK revision.

Files

• general/package/hifb-demo/Config.in — gates on BR2_PACKAGE_HISILICON_OSDRV_HI3520DV200.
• general/package/hifb-demo/hifb-demo.mk — generic-package cross-build of 3 .c files against -lmpi, with --unresolved-symbols=ignore-in-shared-libs so the toolchain doesn't choke on the glibc-only deps libmpi.so pulls (resolved at runtime via glibc-compat).
• general/package/hifb-demo/src/sample_comm_{sys,vo}.c — trimmed verbatim from upstream with attribution headers + a list of what was dropped and why.
• general/package/hifb-demo/src/hifb_demo.c — the demo.
• general/package/hifb-demo/include/ — 18 vendor MPP headers (subset of hisilicon-osdrv-hi3516cv100/files/include/, which is already known to be ABI-compatible with hi3520dv200 — its hi_comm_vo.h carries a literal /***** 3520 ADDed *****/ comment).

Runtime invocation

LD_PRELOAD=/usr/lib/libjpeg.so:/usr/lib/libVoiceEngine.so:\
/usr/lib/libanr.so:/usr/lib/libaec.so:/usr/lib/libresampler.so:\
/usr/lib/libvqev2.so:/usr/lib/libmem.so:/usr/lib/libtde.so \
hifb_demo -t 10

(The LD_PRELOAD chain satisfies cross-.so symbol deps that libmpi.so declares against libc.so.6 via the glibc-compat shim.)

Test plan

• CI build (hi3520dv200_lite) job succeeds with the new package enabled.
• Resulting openipc.hi3520dv200-nor-lite.tgz still fits the 5120 KB rootfs budget.
• On the lab DVR (openipc-hi3520dv200.dlab.torturelabs.com): hifb_demo -t 5 returns 0; /proc/umap/sys shows System State: 0 (initialized) during the run; /dev/fb0 opens (no EPERM); no Unknown symbol lines in dmesg.
• HDMI output visibly shows the color-bar test pattern when a monitor is attached (board-dependent — see "What's deliberately not ported" above for HDMI caveats).

🤖 Generated with Claude Code

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Closing — pushed without explicit ask. The work itself (port of sample_comm_sys.c / sample_comm_vo.c trimmed for hi3520dv200 V2.0.5.1) is on the branch feat/hifb-demo if useful as a reference for a future PR.