input: sensors: fix ap3426 may prevent SoC from sleep

AP3426 may prevent SoC from sleep under the following scenario during
AP3426 workqueue handler:
1. Wake lock cleared after processing sensors interrupt.
2. Proximity sensor interrupt triggered while handling workqueue.
3. Wake lock is hold again.
4. Interrupt flag is cleared by workqueue handler.
5. No one will clear the wake lock again.
This patch handles the above scenario by clear wake lock anyhow after
sensor events are all handled.

Change-Id: Iedbc06bad49c8b6eca5ad54ee0cb97b3add36cf4
Signed-off-by: Oliver Wang <mengmeng@codeaurora.org>