A hardware known issue is observed that KYPD_PWR_N connected to PMIC8921 is blocked by Asustek-owned low detective circuit while battery voltage is under 3.4V. This phenomenon makes KYPD_PWR_N always sensing with high no matter power button is pressed or not. Change power button handling from KYPD_PWN_N into AP_ONKEY connected to GPIO#26 of APQ8064, and remove unnecessary keyboard and pwrkey support from PMIC8921 driver. Change-Id: I35a6b035b89cedbe7efcb80fad53d4921e5d6427 Signed-off-by: paris_yeh <paris_yeh@asus.com>