ARM: dts: stm32: Rename spi-flash/mx66l51235l@N to flash@N on DHCOM SoM

Fix the following dtbs_check warning:
spi-flash@0: $nodename:0: 'spi-flash@0' does not match '^flash(@.*)?$'

Signed-off-by: Marek Vasut <[e-mail]>
Cc: Alexandre Torgue <[e-mail]>
Cc: Patrice Chotard <[e-mail]>
Cc: Patrick Delaunay <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
To: [e-mail]
Signed-off-by: Alexandre Torgue <[e-mail]>

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

···
 	#size-cells = <0>;
 	status = "okay";
 
-	flash0: mx66l51235l@0 {
+	flash0: flash@0 {
 		compatible = "jedec,spi-nor";
 		reg = <0>;
 		spi-rx-bus-width = <4>;

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

···
 	#size-cells = <0>;
 	status = "okay";
 
-	flash0: spi-flash@0 {
+	flash0: flash@0 {
 		compatible = "jedec,spi-nor";
 		reg = <0>;
 		spi-rx-bus-width = <4>;