drm/amd/display: Perform outstanding programming on full updates

[WHY]
In certain scenarios DC can internally trigger back to back full updates
which will miss some required programming that is normally deferred
until post update via optimize_bandwidth.

[HOW]
In back to back update scenarios, wait for pending updates to complete
and perform any strictly required outstanding programming.

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>