dt-bindings: clk: sprd: add bindings for sc9863a clock controller

add a new bindings to describe sc9863a clock compatible string.

Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Link: https://lkml.kernel.org/r/20200304072730.9193-4-zhang.lyra@gmail.com


Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>