stm32mp1: increase device tree size to 28KB

Increase the max device tree size to 28KB to build it
with the TRUSTED_BOARD_BOOT defined nodes.

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Change-Id: I0b48f9085a6ad9c1494eb162de3ad17c124fd8fb
Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/tf-a/+/188765


Reviewed-by: CITOOLS <smet-aci-reviews@lists.codex.cro.st.com>
Reviewed-by: Yann GAUTIER <yann.gautier@st.com>

plat/st/stm32mp1/stm32mp1_def.h

@@ -245,7 +245,7 @@ enum ddr_type {
 					 STM32MP_DTB_SIZE)
 #define TF_A_MAPPING_START		STM32MP_DTB_BASE
 #else /* STM32MP_USE_STM32IMAGE */
-#define STM32MP_BL2_DTB_SIZE		U(0x00006000)	/* 24 KB for DTB */
+#define STM32MP_BL2_DTB_SIZE		U(0x00007000)	/* 28 KB for DTB */
 #define STM32MP_BL2_DTB_BASE		(STM32MP_BL2_BASE - \
 					 STM32MP_BL2_DTB_SIZE)