Fix Pixel HAL for Audio VTS V6.0

Fix error codes returned by stream pause and resume
methods for the offload case.

Fix mmap buffer size check.

Bug: 144575694
Test: atest VtsHalAudioV6_0TargetTest
Change-Id: Iead2ed737a1994fd36f7b0f69ad107afcf14ddd6
Merged-In: Iead2ed737a1994fd36f7b0f69ad107afcf14ddd6