drm/amd/display: Add DML2.1 option to disable DRR clamped P-State Strategies

[WHY & HOW]
When DRR is active with variable refresh rate, add the ability to block DRR
clamped P-State strategies (such as SubVP).

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>