ARM: stm32: Add version variable to DHSOM

Enable insertion of version variable into U-Boot environment on DHSOM,
to make it possible to check U-Boot version e.g. in U-Boot scripts.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/configs/stm32mp15_dhcom_basic_defconfig b/configs/stm32mp15_dhcom_basic_defconfig
index c8093c4..fd261d9 100644
--- a/configs/stm32mp15_dhcom_basic_defconfig
+++ b/configs/stm32mp15_dhcom_basic_defconfig
@@ -97,6 +97,7 @@
 CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_SPL_ENV_IS_NOWHERE=y
+CONFIG_VERSION_VARIABLE=y
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_IP_DEFRAG=y
 CONFIG_TFTP_TSIZE=y