arm: stm32mp1: Implement ECDSA signature verification

The STM32MP ROM provides several service. One of them is the ability
to verify ecdsa256 signatures. Hook the ROM API into the ECDSA uclass.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/arch/arm/mach-stm32mp/Kconfig b/arch/arm/mach-stm32mp/Kconfig
index 8324fa8..5d7eca6 100644
--- a/arch/arm/mach-stm32mp/Kconfig
+++ b/arch/arm/mach-stm32mp/Kconfig
@@ -179,6 +179,15 @@
 	help
 	  Say y to enable STM32 Extended TrustZone Protection
 
+config STM32_ECDSA_VERIFY
+	bool "STM32 ECDSA verification via the ROM API"
+	depends on SPL_ECDSA_VERIFY
+	default y
+	help
+	  Say y to enable the uclass driver for ECDSA verification using the
+	  ROM API provided on STM32MP.
+	  The ROM API is only available during SPL for now.
+
 config CMD_STM32KEY
 	bool "command stm32key to fuse public key hash"
 	default n