ARM: dts: msm: Add GPU static AB voting for msm8916

In concurrent use cases, having a non-zero AB vote from GPU
may help to run the DDR at required power level, which in turn
helps the real-time masters like modem to get enough bandwidth.

Change-Id: I0b5a827ccf7492be318002aa27bbf5ac044940b3
Signed-off-by: Sreedhar Telukuntla <stelukun@codeaurora.org>