drivers: pinctrl: msm: add .irq_enable/disable for irqchip

Add .irq_enable and .irq_disable callbacks for the pinctrl irqchip. In
the absence of these callbacks set, the .irq_mask/.irq_unmask callbacks
are used. However, the parent interrupt controllers for wakeup capable
GPIOs may expect to see these callbacks separately. Hence add these
callbacks but have them perform the same functionality as mask/unmask.

Change-Id: I11437577fb178de94ddc1458bf10647a19f06ba2
Signed-off-by: Lina Iyer <ilina@codeaurora.org>