msm: kgsl: Fix clock gate settings for A4XX

The L1 clocking was not disabled completely for A420. CCU
caching feature requires the L1 clocking to be completely
disabled on A420 hardware as a h/w workaround.

Change-Id: I716d6133d80c912dd3f0d479babfc526f0e758ad
CRs-Fixed: 624275
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>