ARM: dts: msm: Fix MSM8909 QRD display issue

Add PMIC GPIO binding for backlight driven by PWM.
This will fix the suspend resume issue for QRD device.

Change-Id: I9d188a4d9d68908e4a375e929b99a8b6fac103bf
Signed-off-by: Krian Raparthy <kraparth@codeaurora.org>
Signed-off-by: Raghavendra Ambadas <rambad@codeaurora.org>