drm/amd/display: Block optimize on consecutive FAMS enables

[WHY]
It is possible to commit state multiple times in rapid succession with
FAMS enabled; if each of these commits were to set optimized_required,
then the user may see latency.

[HOW]
fw_based_mclk_switching is currently not used in dc->clk_mgr; use it
to track whether the current state has FAMS enabled;
if it has, then do not disable FAMS in prepare_bandwidth, and do not set
optimized_required.

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