drm/amd/display: Create debugging mechanism for Gaming FAMS

[WHY]
To enable FAMS even during gaming sessions.

[HOW]
By leveraging a new dc.debug parameter.

Reviewed-by: Felipe Clark <felipe.clark@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Gianna Binder <gianna.binder@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>