arm: Rename STM32MP15x

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: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/drivers/clk/stm32/Kconfig b/drivers/clk/stm32/Kconfig
index 7dbddd0..c05015e 100644
--- a/drivers/clk/stm32/Kconfig
+++ b/drivers/clk/stm32/Kconfig
@@ -23,7 +23,7 @@
 config CLK_STM32MP1
 	bool "Enable RCC clock driver for STM32MP15"
 	depends on ARCH_STM32MP && CLK
-	default y if STM32MP15x
+	default y if STM32MP15X
 	help
 	  Enable the STM32 clock (RCC) driver. Enable support for
 	  manipulating STM32MP15's on-SoC clocks.