CRAS: audio thread - remove extra local.
CRAS: audio thread - remove extra local.

Don't need the extra local var.  Not having it makes read and write
more similar.

BUG=chromium-os:35272
TEST=make check

Change-Id: Ib20c4565009ca3373779668dbf46ecf947364329
Signed-off-by: Dylan Reid <c791bfe44996c1eed9c7149a0c5f12a86d58eb85@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/40560
Reviewed-by: Chih-Chung Chang <ebe32a3bdce230d12f75781016b6b880113fb486@chromium.org>

drinkcat/adhd,drinkcat/adhd,drinkcat/adhd,drinkcat/adhd,drinkcat/adhd,drinkcat/adhd