stm32mp1: Add support for SPI-NAND boot device

STM32MP1 platform is able to boot from SPI-NAND devices.
These modifications add this support using the new
SPI-NAND framework.

Change-Id: I0d5448bdc4bde153c1209e8043846c0f935ae5ba
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
diff --git a/plat/st/stm32mp1/include/boot_api.h b/plat/st/stm32mp1/include/boot_api.h
index ba5d22f..1f05d0b 100644
--- a/plat/st/stm32mp1/include/boot_api.h
+++ b/plat/st/stm32mp1/include/boot_api.h
@@ -36,6 +36,9 @@
 /* Boot occurred on FMC */
 #define BOOT_API_CTX_BOOT_INTERFACE_SEL_FLASH_NAND_FMC		0x3U
 
+/* Boot occurred on QSPI NAND */
+#define BOOT_API_CTX_BOOT_INTERFACE_SEL_FLASH_NAND_QSPI		0x7U
+
 /**
  * @brief  Possible value of boot context field 'EmmcXferStatus'
  */