ARM: dts: msm: Add pm-qos-latency to GPU dtsi

Currently the code has a fixed CPU latency vote from
the GPU driver. Some targets have different latency
requirements to allow various low latency PC modes.
Allow the CPU latency vote to be programmable based
on target. 701us PM QOS allows the A7 targets select
Low Power Mode which is better in terms of power.
This will help save static leakage of A7 during
graphics use cases.

Change-Id: I38a7ae76a4ebe0c4c98e6bc6d58353989e94c611
Signed-off-by: Prakash Kamliya <pkamliya@codeaurora.org>