stm32mp1: configs: select CONFIG_STM32_SERIAL

Select the serial driver mandatory for the console.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/arch/arm/mach-stm32mp/Kconfig b/arch/arm/mach-stm32mp/Kconfig
index 7efe464..0de9b3e 100644
--- a/arch/arm/mach-stm32mp/Kconfig
+++ b/arch/arm/mach-stm32mp/Kconfig
@@ -42,6 +42,7 @@
 	select PINCTRL_STM32
 	select STM32_RCC
 	select STM32_RESET
+	select STM32_SERIAL
 	select SYS_ARCH_TIMER
 	imply BOOTCOUNT_LIMIT
 	imply BOOTSTAGE