vdpa/mlx5: update mlx_features with driver state check

vdpa/mlx5: update mlx_features with driver state check

Add logic in mlx5_vdpa_set_attr() to ensure the VIRTIO_NET_F_MAC
feature bit is properly set only when the device is not yet in
the DRIVER_OK (running) state.

This makes the MAC address visible in the output of:

 vdpa dev config show -jp

when the device is created without an initial MAC address.

Signed-off-by: Cindy Lu <lulu@redhat.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20260126094848.9601-2-lulu@redhat.com>