clk: st: Include clk.h

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

Cc: Gabriel Fernandez <gabriel.fernandez@st.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/st/clk-flexgen.c

@@ -5,6 +5,7 @@
  * Author:  Maxime Coquelin <maxime.coquelin@st.com> for ST-Microelectronics.
  * License terms:  GNU General Public License (GPL), version 2  */
 
+#include <linux/clk.h>
 #include <linux/clk-provider.h>
 #include <linux/module.h>
 #include <linux/slab.h>