drm/amd/pm: disable manually setting MCLK power level on yellow carp

PMFW provides specific messages for setting fclk freq range thus adjust
the power level. There's misusing of these messages when setting
dpm mclk. Since actually mclk could adjust automatically complying with
fclk, remove standalone support for mclk dpm level setting.

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