clk: qcom: Add the clock controller drivers for SDM660

Add drivers for global clock controller, multimedia clock
controller and peripheral gpu clock driver to support gpu
PLLs and RCGs.
This snapshot of the gcc-sdm660, gpucc-sdm660
and  mmcc-sdm660  driver as of msm-4.14 'commit
4d7da9f5ed3ac19c8 (" Merge "defconfig: sa8195: Enable
config for dyn splash"")'.

Change-Id: Ida7f5b5a3a7aaf275ef9e2d96ee6c67033aad9ca
Signed-off-by: Taniya Das <tdas@codeaurora.org>