ARM: dts: msm: Add LCD backlight configuration for MSM8994 CDP

Configure LPG channel 4 of PMi8994 to output PWM signal to MPP1
which is needed for the LCD backlight. It is made on the assumption
that the initial configuration was made by the bootloader and the PWM
driver changes the output only when the userspace wanted to.

Change-Id: Ie0fa2bae305367729b1ecc56f4528fb5b7851514
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>