feat(st): update STM32MP DT files

This is an alignment with Linux DT files that have been merged in
stm32 tree [1], and will be in Linux 6.7.
The /omit-if-no-ref/ in overlay files are now removed, as already in
pinctrl files.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/atorgue/stm32.git

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: Iab94b0ba7a4a0288ca53d1ae57ab590566967415
diff --git a/fdts/stm32mp25-pinctrl.dtsi b/fdts/stm32mp25-pinctrl.dtsi
index 8d0eaaf..05876a3 100644
--- a/fdts/stm32mp25-pinctrl.dtsi
+++ b/fdts/stm32mp25-pinctrl.dtsi
@@ -6,6 +6,7 @@
 #include <dt-bindings/pinctrl/stm32-pinfunc.h>
 
 &pinctrl {
+	/omit-if-no-ref/
 	usart2_pins_a: usart2-0 {
 		pins1 {
 			pinmux = <STM32_PINMUX('A', 4, AF6)>; /* USART2_TX */