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/stm32mp15xx-dkx.dtsi b/fdts/stm32mp15xx-dkx.dtsi
index 52d4170..f8baa9d 100644
--- a/fdts/stm32mp15xx-dkx.dtsi
+++ b/fdts/stm32mp15xx-dkx.dtsi
@@ -8,6 +8,12 @@
 #include "stm32mp15-ddr3-1x4Gb-1066-binG.dtsi"
 
 / {
+	aliases {
+		serial0 = &uart4;
+		serial1 = &usart3;
+		serial2 = &uart7;
+	};
+
 	memory@c0000000 {
 		device_type = "memory";
 		reg = <0xc0000000 0x20000000>;