clk: moxart: Include clk.h

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

Cc: Jonas Jensen <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/clk-moxart.c

···
  * warranty of any kind, whether express or implied.
  */
 
+#include <linux/clk.h>
 #include <linux/clk-provider.h>
 #include <linux/io.h>
 #include <linux/of_address.h>