media: stagefright: Implement TARGET_DONT_SET_AUDIO_AAC_FORMAT in OMXCodec

On Harmony, when the AAC format is explictly set, HW AAC cannot function.

When TARGET_DONT_SET_AUDIO_AAC_FORMAT : true is set in the BoardConfig.mk,
then this will be operable.

This change can most likely be reverted in a few days,
after all dependant devices have tested:
3333fbb8
(media: stagefright: Implement TARGET_USE_SOFTWARE_AUDIO_AAC in OMXCodec)

thx arcee:)

Change-Id: Icaafaa7cbca0214d5e410a56561cd9d866473f32