Disable fast capture by default for 8974

Fast capture interacts poorly with AEC on 8974.

Frame count is changed from 240 to 480 (10 ms), which means
fast capture thread will not be started by default.
Fast capture thread is only used if frame count is strictly < 10 ms.

Fast capture feature can be re-enabled for specific app testing
by setting property audio_hal.in_period_size=240
in /data/local.prop

Bug: 15591052
Change-Id: I678bf233597c63dc414cab9f64b5ee494eb8701d