arm: stm32mp: detect U-Boot version used to save environment

Imply CONFIG_VERSION_VARIABLE for stm32mp1 target
and test U-Boot version ($env_ver) when the environment was
saved for the last time and to display warning trace.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Change-Id: I4735cdaa63f0d66a5ff23289c87782d8dfd5f1ba

arch/arm/mach-stm32mp/Kconfig

@@ -70,6 +70,7 @@ config TARGET_ST_STM32MP15x
 	imply DISABLE_CONSOLE
 	imply PRE_CONSOLE_BUFFER
 	imply SILENT_CONSOLE
+	imply VERSION_VARIABLE
 	help
 		target the STMicroelectronics board with SOC STM32MP15x
 		managed by board/st/stm32mp1:

include/configs/stm32mp1.h

@@ -165,7 +165,14 @@
 	"splashimage=0xc4300000\0"  \
 	"ramdisk_addr_r=0xc4400000\0" \
 	"altbootcmd=run bootcmd\0" \
-	"env_check=if env info -p -d -q; then env save; fi\0" \
+	"env_check=" \
+		"env exists env_ver || env set env_ver ${ver};" \
+		"if env info -p -d -q; then env save; fi;" \
+		"if test \"$env_ver\" != \"$ver\"; then" \
+		" echo \"*** Warning: old environment ${env_ver}\";" \
+		" echo '* set default: env default -a; env save; reset';" \
+		" echo '* update current: env set env_ver ${ver}; env save';" \
+		"fi;\0" \
 	STM32MP_BOOTCMD \
 	BOOTENV \
 	"boot_net_usb_start=true\0"