[PATCH 3/4] Restructure output format computation for better expandability

From: Werner Sembach
Date: Mon May 03 2021 - 14:22:12 EST

Couples the decission between RGB and YCbCr420 mode and the check if the port
clock can archive the required frequency. Other checks and configuration steps
that where previously done in between can also be done before or after.

This allows for are cleaner implementation of retrying different color

Signed-off-by: Werner Sembach <wse@xxxxxxxxxxxxxxxxxxx>