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/configs/stm32f746-disco_defconfig b/configs/stm32f746-disco_defconfig
index 38caeca..51b779a 100644
--- a/configs/stm32f746-disco_defconfig
+++ b/configs/stm32f746-disco_defconfig
@@ -14,6 +14,7 @@
 CONFIG_AUTOBOOT_PROMPT="Hit SPACE in %d seconds to stop autoboot.\n"
 CONFIG_AUTOBOOT_STOP_STR=" "
 # CONFIG_CMD_IMLS is not set
+CONFIG_CMD_SF=y
 # CONFIG_CMD_FPGA is not set
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_DHCP=y
@@ -26,8 +27,14 @@
 CONFIG_OF_CONTROL=y
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_NETCONSOLE=y
+CONFIG_MTD=y
+CONFIG_DM_SPI_FLASH=y
+CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_DM_ETH=y
 CONFIG_ETH_DESIGNWARE=y
 # CONFIG_SPL_SERIAL_PRESENT is not set
+CONFIG_DM_SPI=y
+CONFIG_STM32_QSPI=y
 CONFIG_OF_LIBFDT_OVERLAY=y
 # CONFIG_EFI_LOADER is not set