clk: si570: Include clk.h

This clock provider uses the consumer API, so include clk.h
explicitly.

Cc: Guenter Roeck <linux@roeck-us.net>
Acked-by: Sören Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/clk-si570.c

@@ -19,6 +19,7 @@
  * GNU General Public License for more details.
  */
 
+#include <linux/clk.h>
 #include <linux/clk-provider.h>
 #include <linux/delay.h>
 #include <linux/module.h>