dts: arm: nxp: Add port property to nxp,lpc-gpio nodes

Add a port property to describe which hardware port a GPIO device node
is describing since we can't tell from the registers (as the registers
are interleaved in the same MMIO space).

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>

dts/arm/nxp/nxp_lpc54xxx.dtsi

@@ -102,6 +102,7 @@
 			label = "GPIO_0";
 			gpio-controller;
 			#gpio-cells = <2>;
+			port = <0>;
 		};
 
 		gpio1: gpio@1 {
@@ -111,6 +112,7 @@
 			label = "GPIO_1";
 			gpio-controller;
 			#gpio-cells = <2>;
+			port = <1>;
 		};
 
 		mailbox0:mailbox@4008b000 {

dts/arm/nxp/nxp_lpc55S1x_common.dtsi

@@ -122,6 +122,7 @@
 		label = "GPIO_0";
 		gpio-controller;
 		#gpio-cells = <2>;
+		port = <0>;
 	};
 
 	gpio1: gpio@1 {
@@ -131,6 +132,7 @@
 		label = "GPIO_1";
 		gpio-controller;
 		#gpio-cells = <2>;
+		port = <1>;
 	};
 
 	flexcomm0: flexcomm@86000 {

dts/arm/nxp/nxp_lpc55S2x_common.dtsi

@@ -123,6 +123,7 @@
 		label = "GPIO_0";
 		gpio-controller;
 		#gpio-cells = <2>;
+		port = <0>;
 	};
 
 	gpio1: gpio@1 {
@@ -132,6 +133,7 @@
 		label = "GPIO_1";
 		gpio-controller;
 		#gpio-cells = <2>;
+		port = <1>;
 	};
 
 	dma0: dma-controller@82000 {

dts/arm/nxp/nxp_lpc55S6x_common.dtsi

@@ -137,6 +137,7 @@
 		label = "GPIO_0";
 		gpio-controller;
 		#gpio-cells = <2>;
+		port = <0>;
 	};
 
 	gpio1: gpio@1 {
@@ -146,6 +147,7 @@
 		label = "GPIO_1";
 		gpio-controller;
 		#gpio-cells = <2>;
+		port = <1>;
 	};
 
 	dma0: dma-controller@82000 {

dts/arm/nxp/nxp_rt6xx_common.dtsi

@@ -73,6 +73,7 @@
 		label = "GPIO_0";
 		gpio-controller;
 		#gpio-cells = <2>;
+		port = <0>;
 	};
 
 	gpio1: gpio@1 {
@@ -82,6 +83,7 @@
 		label = "GPIO_1";
 		gpio-controller;
 		#gpio-cells = <2>;
+		port = <1>;
 	};
 
 	flexspi: spi@134000 {

dts/bindings/gpio/nxp,lpc-gpio.yaml

@@ -17,6 +17,14 @@ properties:
     "#gpio-cells":
       const: 2
 
+    port:
+      type: int
+      required: true
+      description: The GPIO port this node describes
+      enum:
+        - 0
+        - 1
+
 gpio-cells:
   - pin
   - flags