kernel: strengthen smmu validation for QLI platforms

[smuppand]

This PR extends the SMMU testcase under Runner/suites/Kernel/Baseport/smmu.

Why this PR is needed:
The existing smmu test only checked whether dmesg | grep iommu returned any output. That is too weak for QLI platforms and can both miss real issues and misrepresent actual SMMU status. On QLI systems, /sys/kernel/debug/iommu may be absent even when SMMU is functioning correctly, so relying on upstream-style
debugfs expectations is not sufficient.

What this PR changes:

• replaces the basic dmesg grep logic with stronger runtime validation
• checks required SMMU and IOMMU kernel configs
• validates /sys/kernel/iommu_groups presence and group enumeration
• validates platform devices attached to IOMMU groups
• checks critical DMA masters such as GPU, display, camera, video, UFS, USB, ethernet, and audio, when present, for IOMMU protection
• uses shared functestlib helpers instead of raw one-off log parsing
• uses scan_dmesg_errors and get_kernel_log for SMMU or IOMMU related log analysis instead of a plain dmesg | grep iommu

Why this is useful:
On QLI hardware, the most meaningful SMMU validation is not just whether a log line exists, but whether:

• IOMMU groups are created
• DMA-capable devices are actually attached to those groups
• critical masters are not silently running without protection
• kernel logs do not show bypass, passthrough, or fault-related issues

This makes the testcase much closer to real SMMU runtime validation on target systems and helps catch regressions that the previous test would not detect.

[vnarapar]

LGTM