drm/virtio: Create Dumb BOs as guest Blobs (v3)

If support for Blob resources is available, then dumb BOs created
by the driver can be considered as guest Blobs.

v2: Don't skip transfer and flush commands as part of plane update
as the device may have created a shared mapping. (Gerd)

v3: Don't create dumb BOs as Guest blobs if Virgl is enabled. (Gurchetan)

Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Acked-by: Gurchetan Singh <gurchetansingh@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20210413052614.2486768-1-vivek.kasireddy@intel.com


Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>