clk: sprd: Add dt-bindings include file for SC9860

This file defines all SC9860 clock indexes, it should be included in the
device tree in which there's device using the clocks.

Signed-off-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>