drm/radeon/cik: enable/disable vce cg when encoding v2

Some of the vce clocks are automatic, others need to
be manually enabled.  For ease, just disable cg when
vce is active.

v2: rebased

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

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

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