clk: hisilicon: add CRG driver for Hi3798CV200 SoC

Add CRG driver for Hi3798CV200 SoC. CRG(Clock and Reset
Generator) module generates clock and reset signals used
by other module blocks on SoC.

Signed-off-by: Jiancheng Xue <xuejiancheng@hisilicon.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>