arm: Rename STM32MP13x

CONFIG options must not use lower-case letter. Convert this and related
ones to upper case.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Igor Opaniuk <igor.opaniuk@foundries.io>
diff --git a/drivers/clk/stm32/Kconfig b/drivers/clk/stm32/Kconfig
index 7a34ea2..7dbddd0 100644
--- a/drivers/clk/stm32/Kconfig
+++ b/drivers/clk/stm32/Kconfig
@@ -31,7 +31,7 @@
 config CLK_STM32MP13
 	bool "Enable RCC clock driver for STM32MP13"
 	depends on ARCH_STM32MP && CLK
-	default y if STM32MP13x
+	default y if STM32MP13X
 	select CLK_STM32_CORE
 	help
 	  Enable the STM32 clock (RCC) driver. Enable support for