drm/radeon: fix VCE fence command

Due to a type mismatch that causes an implicit type conversion, the
upper 32 bits of the GPU address have been zeroed out when adding to the
command buffer.

Picked up by Coverity - CID 1198624.

Signed-off-by: Christoph Jaeger <christophjaeger@linux.com>

diff --cc drivers/gpu/drm/radeon/radeon_vce.c
Simple merge