drm/virtio: switch virtio_gpu_wait_ioctl() to gem helper.

drm/virtio: switch virtio_gpu_wait_ioctl() to gem helper.

[ Upstream commit 29cf12394c0565d7eb1685bf0c1b4749aa6a8b66 ]

Use drm_gem_reservation_object_wait() in virtio_gpu_wait_ioctl().
This also makes the ioctl run lockless.

v9: fix return value.
v5: handle lookup failure.
v2: use reservation_object_test_signaled_rcu for VIRTGPU_WAIT_NOWAIT.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20190829103301.3539-3-kraxel@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>