csky: Replace <linux/clk-provider.h> by <linux/of_clk.h>

The C-Sky platform code is not a clock provider, and just needs to call
of_clk_init().

Hence it can include <linux/of_clk.h> instead of <linux/clk-provider.h>.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>