drm/nouveau: wait for moving fence after pinning v2

commit 17b11f71 upstream.

We actually need to wait for the moving fence after pinning
the BO to make sure that the pin is completed.

v2: grab the lock while waiting

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
References: https://lore.kernel.org/dri-devel/20210621151758.2347474-1-daniel.vetter@ffwll.ch/
CC: stable@kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20210622114506.106349-1-christian.koenig@amd.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>