configs: stm32mp13: activate RTC support

Activate the RTC driver in STM32MP13x config.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/configs/stm32mp13_defconfig b/configs/stm32mp13_defconfig
index 4707315..5f88f08 100644
--- a/configs/stm32mp13_defconfig
+++ b/configs/stm32mp13_defconfig
@@ -48,6 +48,8 @@
 CONFIG_RESET_SCMI=y
 CONFIG_DM_RNG=y
 CONFIG_RNG_OPTEE=y
+CONFIG_DM_RTC=y
+CONFIG_RTC_STM32=y
 CONFIG_SERIAL_RX_BUFFER=y
 CONFIG_SYSRESET_PSCI=y
 CONFIG_TEE=y