input: touchscreen: bu21150: add touch-to-wake feature

Touch-to-wake feature requires IRQ responsive when device is in
suspend mode. Also use of power management APIs prevents device
from going into suspend when users touch the screen to wake the
device up.

Change-Id: Ie11993318029471eddfc1a0ae92759207d899db7
Signed-off-by: Chun Zhang <chunz@codeaurora.org>