drm/amd/powerplay: correct Navi10 VCN powergate control (v2)

No VCN DPM bit check as that's different from VCN PG. Also
no extra check for possible double enablement/disablement
as that's already done by VCN.

v2: check return value of smu_feature_set_enabled

Signed-off-by: Evan Quan <[email protected]>
Reviewed-by: Kenneth Feng <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
1 file changed