clk: stm32f7: add clock .get_rate() callback

Add clock framework .get_rate callback.
This step will allow to convert all drivers which was using
proprietary clock_get() to use clock framework .get_rate().

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Acked-by: Vikas MANOCHA <vikas.manocha@st.com>

arch/arm/include/asm/arch-stm32f7/rcc.h

@@ -8,6 +8,8 @@
 #ifndef _STM32_RCC_H
 #define _STM32_RCC_H
 
+#include <dt-bindings/mfd/stm32f7-rcc.h>
+
 /*
  * RCC AHB1ENR specific definitions
  */