ARM: dts: msm: Add GEN4 FG device for PM855B

Add the required configuration for GEN4 FG device that is present
on PM855B. FG provides battery parameters like voltage, current,
resistance, temperature and exposes it for the clients when
requested through the power supply class device.

Change-Id: I2662e17651a6da837b24f7eb1b7719d474d519d0
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>