drm/amd/display: Disable MPC split by default on special asic

drm/amd/display: Disable MPC split by default on special asic

[WHY]
All of pipes will be used when the MPC split enable on the dcn
which just has 2 pipes. Then MPO enter will trigger the minimal
transition which need programe dcn from 2 pipes MPC split to 2
pipes MPO. This action will cause lag if happen frequently.

[HOW]
Disable the MPC split for the platform which dcn resource is limited

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Acked-by: Alan Liu <haoping.liu@amd.com>
Signed-off-by: Zhikai Zhai <zhikai.zhai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>