drm/virtio: Remove multiple blank lines

This patch fixes the checkpatch.pl check:

virtgpu_drv.c:116: CHECK: Please don't use multiple blank lines
virtgpu_vq.c:599: CHECK: Please don't use multiple blank lines
virtgpu_prime.c:42: CHECK: Please don't use multiple blank lines

Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/c43a006f2ed93a16fe824b4a2686a2d5e2ef56f5.1519343668.git.rodrigosiqueiramelo@gmail.com


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