pinctrl: qcom: Add back irq_disable callback from msmmgpio irqchip

Commit 80654a55 ("pinctrl: qcom: Remove irq_disable callback
from msmmgpio irqchip") removed irq_disable callback and started
using irq_mask instead.

msmgpio's parent PDC irq_chip will still use irq_disable and irq_mask
callbacks separately. Add irq_disable callback back to allow it to reach
its parent PDC irqchip.

Change-Id: I256792c50ac7d4eea2d1ba0e76e13081bda65a7c
Signed-off-by: Maulik Shah <mkshah@codeaurora.org>