msm: kgsl: Set DDR qos level based on GPU bus IB vote

For the highest IB vote, enable DDR qos level which increases
performance by disabling certain DDR low power states.

Change-Id: Iaabc99f724ca6f2b8de2a95da00f73608209e97f
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>