clk: qcom: Add Global Clock controller (GCC) driver for SDM660

Add support for the global clock controller found on SDM660
based devices. This should allow most non-multimedia device
drivers to probe and control their clocks.
Based on CAF implementation.

Signed-off-by: Taniya Das <tdas@codeaurora.org>
[craig: rename parents to fit upstream, and other cleanups]
Signed-off-by: Craig Tatlor <ctatlor97@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
[sboyd@kernel.org: Rename gcc_660 to gcc_sdm660 and fix numbering of
defines to avoid duplicates]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>