drm/virtio: Change value of feature ALLOW_P2P to 13

Original value 31 is reserved for extensions to the queue and feature
negotiation mechanisms by virtio spec (Chapter 2, Section 2.2). To avoid
violation to the spec, change the value to 13, which is within the range
for specific virtio device type.

Test-done:
- Boot AAOS with dGPU SR-IOV VF and virtio-GPU backed by dGPU display.

Tracked-On: OAM-124694
Signed-off-by: Weifeng Liu <weifeng.liu@intel.com>

include/uapi/linux/virtio_gpu.h

@@ -75,7 +75,7 @@
 
 #define VIRTIO_GPU_F_VBLANK              7
 
-#define VIRTIO_GPU_F_ALLOW_P2P           31
+#define VIRTIO_GPU_F_ALLOW_P2P           13
 
 /*
  * VIRTIO_GPU_CMD_FLUSH_SPRITE