msm: qpnp-power-on: Warn a long key press with vibration

Unintended power off may happen by long key press. So if power key is pressed
for a specific time, vibe for the notification.

Change-Id: Idfb31e2b8999be39b2f937a331e9b146b845278c
Signed-off-by: Devin Kim <dojip.kim@lge.com>