ARM: dts: stm32: Rename eth@N to ethernet@N on DHCOM SoM

Fix the following dtbs_check warning:
eth@1,0: $nodename:0: 'eth@1,0' does not match '^ethernet(@.*)?$'
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: Patrick Delaunay <patrick.delaunay@foss.st.com>
Cc: kernel@dh-electronics.com
Cc: linux-stm32@st-md-mailman.stormreply.com
To: linux-arm-kernel@lists.infradead.org
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi

@@ -150,7 +150,7 @@ &fmc {
 	pinctrl-1 = <&fmc_sleep_pins_b>;
 	status = "okay";
 
-	ksz8851: ks8851mll@1,0 {
+	ksz8851: ethernet@1,0 {
 		compatible = "micrel,ks8851-mll";
 		reg = <1 0x0 0x2>, <1 0x2 0x20000>;
 		interrupt-parent = <&gpioc>;