MediaCodec: unify KEY_MAX_OUTPUT_CHANNEL_COUNT and AAC variant

Make KEY_MAX_OUTPUT_CHANNEL_COUNT behave like
KEY_AAC_MAX_OUTPUT_CHANNEL_COUNT for AAC decoder.

Bug: 198197610
Test: atest DecoderTestAacFormat
Change-Id: Ie0c78d965902fc4561ecfd0bbe3a1d0c0cf457c8
3 files changed