feat(plat/st): add a new DDR firewall management

Based on FCONF framework, define DDR firewall regions
from firmware config file instead of static defines.

Change-Id: I471e15410ca286d9079a86e3dc3474f66d37b5ab
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
diff --git a/plat/st/stm32mp1/stm32mp1_private.c b/plat/st/stm32mp1/stm32mp1_private.c
index 1af0075..e4065c1 100644
--- a/plat/st/stm32mp1/stm32mp1_private.c
+++ b/plat/st/stm32mp1/stm32mp1_private.c
@@ -452,6 +452,7 @@
 }
 #endif
 
+#if STM32MP_USE_STM32IMAGE
 /* Get the non-secure DDR size */
 uint32_t stm32mp_get_ddr_ns_size(void)
 {
@@ -472,3 +473,4 @@
 
 	return ddr_ns_size;
 }
+#endif /* STM32MP_USE_STM32IMAGE */