This adds a mutex lock for both DPM/PP around the changes in
power gating state so that userspace can poll registers without
a race condition on power state.
Signed-off-by: NTom St Denis <tom.stdenis@amd.com>
Reviewed-by: NRex Zhu <Rex.Zhu@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>