drm/amd/display: Block FPO According to Luminance Delta

drm/amd/display: Block FPO According to Luminance Delta

[Description]
 - Block FPO if the max stretch refresh rate is low enough
   to cause a flicker by storing the maximum safe refresh
   decrease from nominal in stream.
 - Brought over various Freesync Luminance functions to dc. Use these
   new functions to block fpo if we will flicker.
 - Generalized increase/reduce dependent functions to reduce code clutter
   and allow for easier use.
 - Added a debug option to enable the feature. Disabled by default.

Co-authored-by: Ethan Bitnun <etbitnun@amd.com>
Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Ethan Bitnun <etbitnun@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>