ARM: dts: msm: Add pinctrl for PM8350C GPIO 9 on Lahaina platforms

Output of PWM channel 4 is used for external backlight control of
display panel. Add pinctrl configuration for PM8350C GPIO 9 such that
it is capable of outputting PWM 4's output. This pinctrl configuration
is used by display driver for external backlight control.

Change-Id: Ie9e1a1bf02d8caecde61861dc4528fa0f414a995