Revert "Rename AudioGain.useInChannelMask -> isInput"

This reverts commit e028aed5290a98f5e8523ce37595e28aaa838c63.

Reason for revert: Android Auto regression b/194987848

Change-Id: I80ce258defca1a1c75e8a4c656690bd8cf809331
(cherry picked from commit 05399f489aece403775f34cd2c2233243e2d5654)
5 files changed