clk: hisilicon: add common clock support

Enable common clock driver of Hi3620 SoC. clkgate-seperated driver is
used to support the clock gate that enable/disable/status registers
are seperated.

Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>

diff --cc Documentation/devicetree/bindings/clock/hi3620-clock.txt
Simple merge

diff --cc drivers/clk/Makefile
Simple merge

diff --cc drivers/clk/hisilicon/Makefile
Simple merge

diff --cc drivers/clk/hisilicon/clk-hi3620.c
Simple merge

diff --cc drivers/clk/hisilicon/clk.c
Simple merge

diff --cc drivers/clk/hisilicon/clk.h
Simple merge

diff --cc drivers/clk/hisilicon/clkgate-separated.c
Simple merge

diff --cc include/dt-bindings/clock/hi3620-clock.h
Simple merge