feat(stm32mp2): add BL31 device tree support

BL31 will need to access a device tree for several configurations (UART,
GIC, OTP mapping...).
Create a BL31 device tree (SOC_FW_CONFIG). It is loaded in DDR, in a
spare area.

Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Signed-off-by: Maxime Méré <maxime.mere@foss.st.com>
Change-Id: I320a05859e1aa3dd8db9a274e7201075a8c250c2
diff --git a/plat/st/stm32mp2/bl2_plat_setup.c b/plat/st/stm32mp2/bl2_plat_setup.c
index 345850b..2fabc41 100644
--- a/plat/st/stm32mp2/bl2_plat_setup.c
+++ b/plat/st/stm32mp2/bl2_plat_setup.c
@@ -280,6 +280,7 @@
 	unsigned int i;
 	const unsigned int image_ids[] = {
 		BL31_IMAGE_ID,
+		SOC_FW_CONFIG_ID,
 		BL32_IMAGE_ID,
 		BL33_IMAGE_ID,
 		HW_CONFIG_ID,
@@ -345,6 +346,7 @@
 				break;
 
 			case HW_CONFIG_ID:
+			case SOC_FW_CONFIG_ID:
 				break;
 
 			default: