clk: hisilicon: add CRG driver for hi3519 soc

The CRG(Clock and Reset Generator) block provides clock
and reset signals for other modules in hi3519 soc.

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