msm: kgsl: Double check that wait didn't get scheduled out

If KGSL times out (due to cond_resched()) while waiting on
a GMU status register, double check if the value was
successfully set before returning error.

Change-Id: I72b866434716c9a9175b4fe3fb7b407feb2ca164
Signed-off-by: Carter Cooper <ccooper@codeaurora.org>