ARM: SPI: stm32: add stm32f746 qspi driver

This patch adds support for the QSPI IP found in stm32f7 devices.

Signed-off-by: Michael Kurz <michi.kurz@gmail.com>
diff --git a/arch/arm/include/asm/arch-stm32f7/rcc.h b/arch/arm/include/asm/arch-stm32f7/rcc.h
index 23eec5e..0f8d50b 100644
--- a/arch/arm/include/asm/arch-stm32f7/rcc.h
+++ b/arch/arm/include/asm/arch-stm32f7/rcc.h
@@ -31,6 +31,7 @@
  * RCC AHB3ENR specific definitions
  */
 #define RCC_AHB3ENR_FMC_EN		BIT(0)
+#define RCC_AHB3ENR_QSPI_EN             BIT(1)
 
 /*
  * RCC APB1ENR specific definitions