boards: st: stm32N6 boards xspi-nor-flash DTS configuration

This PR defines the "st,stm32-xspi-nor" compatible Node
and the "st,stm32-xspi-psram" compatible Node
in conformance to the DTS specifications
Includes the size property (in Bits) of the external memory device

Signed-off-by: Francois Ramu <francois.ramu@st.com>

Author: FRASTM

boards/st/nucleo_n657x0_q/nucleo_n657x0_q_common.dtsi

@@ -235,9 +235,10 @@ zephyr_udc0: &usbotg_hs1 {
 		 <&rcc STM32_CLOCK(AHB5, 13)>;
 	status = "okay";
 
-	mx25um51245g: ospi-nor-flash@70000000 {
+	mx25um51245g: ospi-nor-flash@0 {
 		compatible = "st,stm32-xspi-nor";
-		reg = <0x70000000 DT_SIZE_M(64)>; /* 512 Mbits */
+		reg = <0>;
+		size = <DT_SIZE_M(512)>; /* 512 Mbits */
 		ospi-max-frequency = <DT_FREQ_M(200)>;
 		spi-bus-width = <XSPI_OCTO_MODE>;
 		data-rate = <XSPI_DTR_TRANSFER>;

boards/st/stm32n6570_dk/stm32n6570_dk_common.dtsi

@@ -250,9 +250,10 @@ zephyr_udc0: &usbotg_hs1 {
 		 <&rcc STM32_CLOCK(AHB5, 13)>;
 	status = "okay";
 
-	memc: aps256xxn_obr: memory@90000000 {
+	memc: aps256xxn_obr: memory@0 {
 		compatible = "st,stm32-xspi-psram";
-		reg = <0x90000000 DT_SIZE_M(32)>; /* 256 Mbits */
+		reg = <0>;
+		size = <DT_SIZE_M(256)>; /* 256 Mbits */
 		fixed-latency;
 		io-x16-mode;
 		read-latency = <4>;
@@ -273,9 +274,10 @@ zephyr_udc0: &usbotg_hs1 {
 		 <&rcc STM32_CLOCK(AHB5, 13)>;
 	status = "okay";
 
-	mx66uw1g45g: ospi-nor-flash@70000000 {
+	mx66uw1g45g: ospi-nor-flash@0 {
 		compatible = "st,stm32-xspi-nor";
-		reg = <0x70000000 DT_SIZE_M(128)>; /* 1 Gbits */
+		reg = <0>;
+		size = <DT_SIZE_M(1024)>; /* 1Gbits */
 		ospi-max-frequency = <DT_FREQ_M(200)>;
 		spi-bus-width = <XSPI_OCTO_MODE>;
 		data-rate = <XSPI_DTR_TRANSFER>;