audio: Add check for MMap buffer size to the default implementation

Add documentation and check that 'minSizeFrames' parameter
is a positive value. Previously a similar check was added
to Pixel HAL.

Bug: 141989952
Test: atest VtsHalAudioV6_0TargetTest
Change-Id: I526431fc214f7f5bc424f0c9e4c890cf918ca2b2