feat(stm32mp1): add define for external scratch buffer for nand devices

Override the default platform function to use an external buffer
on STM32MP13 platform.
It allows to use a temporary buffer located at the SRAM1 memory end.

Signed-off-by: Lionel Debieve <lionel.debieve@foss.st.com>
Change-Id: Ibd84bb336c60af24608268916b3a18bb5a0fa3db
diff --git a/plat/st/stm32mp1/stm32mp1_def.h b/plat/st/stm32mp1/stm32mp1_def.h
index 542895a..06660ce 100644
--- a/plat/st/stm32mp1/stm32mp1_def.h
+++ b/plat/st/stm32mp1/stm32mp1_def.h
@@ -194,6 +194,12 @@
 /* Define maximum page size for NAND devices */
 #define PLATFORM_MTD_MAX_PAGE_SIZE	U(0x1000)
 
+/* Define location for the MTD scratch buffer */
+#if STM32MP13
+#define STM32MP_MTD_BUFFER		(SRAM1_BASE + \
+					 SRAM1_SIZE - \
+					 PLATFORM_MTD_MAX_PAGE_SIZE)
+#endif
 /*******************************************************************************
  * STM32MP1 device/io map related constants (used for MMU)
  ******************************************************************************/