drm/amd/pm: do not issue message while write "r" into pp_od_clk_voltage

We should commit the value after restore them back to default as well.

$ echo "r" > pp_od_clk_voltage
$ echo "c" > pp_od_clk_voltage

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