drm/amdgpu: Check vcn state before profile switch

The patch uses power state of VCN instances for requesting video
profile.

In idle worker of a vcn instance, when there is no outstanding
submisssion or fence, the instance is put to power gated state. When
all instances are powered off that means video profile is no longer
required. A request is made to turn off video profile.

A job submission starts with begin_use of ring, and at that time
vcn instance state is changed to power on. Subsequently a check is
made for active video profile, and if not active, a request is made.

Fixes: 3b669df9 ("drm/amdgpu/vcn: adjust workload profile handling")
Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Sathishkumar S <sathishkumar.sundararaju@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>