arm: stm32mp: add config for STM32IMAGE support

By default for trusted boot with TF-A, U-Boot (u-boot-nodtb)
is located in FIP container with its device tree and with
the secure monitor (provided by TF-A or OP-TEE).
The FIP file is loaded by TF-A BL2 and each components is
extracted at the final location.

This patch add CONFIG_STM32MP15x_STM32IMAGE to request the
STM32 image generation for SOC STM32MP15x
when FIP container is not used (u-boot.stm32 is loaded by TF-A
as done previously to keep the backward compatibility).

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/arch/arm/mach-stm32mp/Kconfig b/arch/arm/mach-stm32mp/Kconfig
index ace07fd..8324fa8 100644
--- a/arch/arm/mach-stm32mp/Kconfig
+++ b/arch/arm/mach-stm32mp/Kconfig
@@ -56,6 +56,13 @@
 		dual core A7 for STM32MP157/3, monocore for STM32MP151
 		target all the STMicroelectronics board with SOC STM32MP1 family
 
+config STM32MP15x_STM32IMAGE
+	bool "Support STM32 image for generated U-Boot image"
+	depends on STM32MP15x && TFABOOT
+	help
+		Support of STM32 image generation for SOC STM32MP15x
+		for TF-A boot when FIP container is not used
+
 choice
 	prompt "STM32MP15x board select"
 	optional