msm: kgsl: Add a feature ADRENO_PERFCTRL_RETAIN

Add a ADRENO_PERFCTRL_RETAIN feature to enable it
target specific. This feature will allows to retain
RBBM perf control enable setting value across power
collapse interval. This is needed to start counting
perf counter after the IFPC.

Also enable this feature for A608 GPU.

Change-Id: I79ba7cfa5afb7d16745673eb740b9cddc229d091
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>