drm/virtio: Replace 'unsigned' for 'unsigned int'

This patch fixes the checkpatch.pl warning:

drivers/gpu/drm/virtio/virtgpu_display.c:64: WARNING: Prefer 'unsigned
int' to bare use of 'unsigned'
...

Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/ac9c4110785e6519801d44c57d4f05c3e0cdad53.1519343668.git.rodrigosiqueiramelo@gmail.com


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