drm/amd/display: For FAMS2 don't program P-State force from driver

P-State force programming is handled entirely by FW in FAMS2.  Remove
any programming from driver side to prevent incorrect programming from
driver side (which may override FW programming)

Signed-off-by: Alvin Lee <Alvin.Lee2@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>