ARM: dts: msm8994-pinctrl: Add num_irqs for msm_gpio node

The msm gpio chip can also be used as a interrupt chip and
needs the num_irqs property to be defined.

Change-Id: I47c9dee3b1d5f2534e79a5e5623a462718ed492d
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>