feat(stm32mp2-fdts): add BL31 info in fw-config

Add BL31 load address (beginning on SYSRAM) and size in fw-config DT
file.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Maxime Méré <maxime.mere@foss.st.com>
Change-Id: I2fcd8d326f394090401ac59b47216d59d3e911bc
diff --git a/fdts/stm32mp25-fw-config.dtsi b/fdts/stm32mp25-fw-config.dtsi
index b187ad2..102980d 100644
--- a/fdts/stm32mp25-fw-config.dtsi
+++ b/fdts/stm32mp25-fw-config.dtsi
@@ -25,6 +25,12 @@
 			id = <BL33_IMAGE_ID>;
 		};
 
+		soc_fw {
+			load-address = <0x0 STM32MP_SYSRAM_BASE>;
+			max-size = <STM32MP_BL31_SIZE>;
+			id = <BL31_IMAGE_ID>;
+		};
+
 		tos_fw {
 			id = <BL32_IMAGE_ID>;
 		};