msm: kgsl: Optimize clock call order

Eliminate the possibility of duplicate RPM calls while using
set_rate in addition to prepare/unprepare.

Change-Id: I74905c2f79b7f78047798b6e8022ded2fce5bf33
Signed-off-by: Lucille Sylvester <lsylvest@codeaurora.org>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>