mach-stm32: Enable SPL_RESET_SUPPORT flag

Since commit 0e373c0ade8c ("spl: add SPL_RESET_SUPPORT"),
reset is supported in SPL, enable this flag for STM32F SoCs family.

This allows to remove a specific case in RCC mfd driver.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/arch/arm/mach-stm32/Kconfig b/arch/arm/mach-stm32/Kconfig
index 1353284..759f545 100644
--- a/arch/arm/mach-stm32/Kconfig
+++ b/arch/arm/mach-stm32/Kconfig
@@ -48,6 +48,7 @@
 	imply SPL_OS_BOOT
 	select SPL_PINCTRL
 	select SPL_RAM
+	select SPL_RESET_SUPPORT
 	select SPL_SERIAL_SUPPORT
 	select SPL_SYS_MALLOC_SIMPLE
 	select SPL_TIMER