HAL: Add forgotten {} after if

My previous fix to close resources on error was buggy.
The if did not have {} around the `then` statement.

Thus sndmonitor was broken.

Test: vts-tradefed run vts --module VtsHalAudioV2_0Target
Test: call/play music/record/video...
Bug: 38186481
Change-Id: I643c38c3bed76c63359348aeaccb774b64bf6f7c
Signed-off-by: Kevin Rocard <krocard@google.com>