msm: kgsl: Add CP_WAIT_FOR_IDLE packet before updating timestamp

HW workaround to resolve MMU pagefault caused by memory
freeing early before GPU completes it.

This is race condition where timestamp is getting updated
and the event handler runs before the GPU actually got done
with the timestamp, hence freeing the buffer early while GPU
still not completed with it.

Signed-off-by: Anshuman Dani <adani@codeaurora.org>

Conflicts:

	drivers/gpu/msm/adreno_ringbuffer.c
Change-Id: I6d338d7dca680f57f2c39ed5a14381b261bf8bce

Signed-off-by: Vikram Orre <vorre@codeaurora.org>
msm: kgsl: Add cache flush for A20x

Adding extra cache flush command to make sure that CP block
gets event from RB all the time to avoid race conditions because of
clock switches. this is to improve stability on 8x25 target.

Signed-off-by: Rajesh Kemisetti <rajeshk@codeaurora.org>

Conflicts:

	drivers/gpu/msm/adreno_ringbuffer.c
Change-Id: Ie411be46fa166864073d35c50085a8f2506d0eb8

Signed-off-by: Vikram Orre <vorre@codeaurora.org>