msm: kgsl: Enable Peak Power Detection for A430v2

Peak Power Detection(PPD) is a feature to mitigate peak current
conditions on the GPU. The throttling happens only in turbo mode,
hence mask the throttle signal and reset the logic around clock switch
boundaries. Also add the registers to snapshot for A430v2.

Change-Id: I6235d10c0ed348e6a45c3f4ea44de984155f2b62
Signed-off-by: Suman Tatiraju <sumant@codeaurora.org>