Add struct virtio_net_dev Entry in struct vm_t

This commit adds a struct `virtio_net_dev` entry
within the struct `vm_t` structure to facilitate
the implementation of the virtio-net device.
This addition is necessary to integrate and manage
the virtio-net device within the broader context
of the virtual machine.

Author: jimmylu890303

src/vm.h

@@ -5,6 +5,7 @@
 #include "pci.h"
 #include "serial.h"
 #include "virtio-blk.h"
+#include "virtio-net.h"
 
 typedef struct {
     int kvm_fd, vm_fd, vcpu_fd;
@@ -15,6 +16,7 @@ typedef struct {
     struct pci pci;
     struct diskimg diskimg;
     struct virtio_blk_dev virtio_blk_dev;
+    struct virtio_net_dev virtio_net_dev;
     void *priv;
 } vm_t;