Reduce the number of PCM data reads for aptX and aptX HD

For every periodic aptX / aptX HD data packet, use a single read
operation for all PCM data that needs to be encoded, instead of
using multiple reads of smaller blocks of data.

Bug: 70899260
Test: Manual: stream to aptX/aptX HD headset, change the sample rate
Change-Id: Ifcb8302589f24f5d7ab89c645c50d6905197fb7f
Merged-In: Ifcb8302589f24f5d7ab89c645c50d6905197fb7f
(cherry picked from commit fbfffe53)