[Why]
The MPC memory blocks in DCN3 should be powered down completely when
they are not in use. This will reduce power consumption.

[How]
This commits changes behaviour for dcn3 and does the following:
1. Write to MPC_RMU<X>_LOW_PWR_MODE and MPCC_OGAM_MEM_LOW_PWR_MODE to
   automatically shut down memory when not in use
2. mpc3_power_on_shaper_3dlut and mpc3_power_on_ogam_lut are called
   to disable force power on when configuration finishes
3. Added a debug option to allow this behaviour to be turned off
Signed-off-by: Jacky Liao <ziyu.liao@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>