drm/amd/pm: remove vcn/jpeg powergating feature checking for vangogh

VCN/JPEG PG won't be a feature mask bit which exposed by vangogh smu
firmware. So remove it.

Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>