pinctrl: qcom: Add irq_enable callback for msm gpio

Introduce the irq_enable callback which will be same as irq_unmask
except that it will also clear the status bit before unmask.

This will help in clearing any erraneous interrupts that would
have got latched when the interrupt is not in use.

There may be devices like UART which can use the same gpio line
for data rx as well as a wakeup gpio when in suspend. The data that
was flowing on the line may latch the interrupt and when we enable
the interrupt before going to suspend, this would trigger the
unexpected interrupt. This change helps clearing the interrupt
so that these unexpected interrupts gets cleared.

Change-Id: I017badff8d5b993599d7e7240ed4702ff4b344ad
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
Signed-off-by: Kyle Yan <kyan@codeaurora.org>