Cleanup mode matching logic

This change reorders and renames parameters for internal mode matching
methods used by DrmGpuDisplayManager to improve readability.
Documentation for the updated parameters is added. This change also
modifies conditional logic around mode matching for more straightforward
early-return and fallback structure. This change is cleanup only, and
should not affect behavior.

Bug: b:321725211
Change-Id: I273126d06305764d204019f0573c4579d40f1430
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5606975


Reviewed-by: Gil Dekel <gildekel@chromium.org>
Commit-Queue: Andrew Wolfers <aswolfers@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1312195}