net: Consolidate vhost feature bits into vhost_net structure

Previously, the vhost_net_get_feature_bits() function in
hw/net/vhost_net.c used a large switch statement to determine
the appropriate feature bits based on the NetClientDriver type.

This created unnecessary coupling between the generic vhost layer
and specific network backends (like TAP, vhost-user, and
vhost-vdpa).

This patch moves the definition of vhost feature bits directly into the
vhost_net structure for each relevant network client.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

include/net/vhost-vdpa.h

@@ -14,6 +14,4 @@
 
 #define TYPE_VHOST_VDPA "vhost-vdpa"
 
-extern const int vdpa_feature_bits[];
-
 #endif /* VHOST_VDPA_H */

include/net/vhost_net.h

@@ -12,6 +12,7 @@ typedef struct VhostNetOptions {
     NetClientState *net_backend;
     uint32_t busyloop_timeout;
     unsigned int nvqs;
+    const int *feature_bits;
     void *opaque;
 } VhostNetOptions;