ARM: dts: pxa*: Fix serial port names

There's a preferred node name for serial ports, and it's not "uart":

  pxa910-dkb.dt.yaml: uart@d4017000: $nodename:0: 'uart@d4017000'
      does not match '^serial(@[0-9a-f,]+)*$'
  ...
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200320174107.29406-3-lkundrak@v3.skSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm/boot/dts/pxa168.dtsi

@@ -55,7 +55,7 @@ timer0: timer@d4014000 {
 				interrupts = <13>;
 			};
 
-			uart1: uart@d4017000 {
+			uart1: serial@d4017000 {
 				compatible = "mrvl,mmp-uart";
 				reg = <0xd4017000 0x1000>;
 				interrupts = <27>;
@@ -64,7 +64,7 @@ uart1: uart@d4017000 {
 				status = "disabled";
 			};
 
-			uart2: uart@d4018000 {
+			uart2: serial@d4018000 {
 				compatible = "mrvl,mmp-uart";
 				reg = <0xd4018000 0x1000>;
 				interrupts = <28>;
@@ -73,7 +73,7 @@ uart2: uart@d4018000 {
 				status = "disabled";
 			};
 
-			uart3: uart@d4026000 {
+			uart3: serial@d4026000 {
 				compatible = "mrvl,mmp-uart";
 				reg = <0xd4026000 0x1000>;
 				interrupts = <29>;

arch/arm/boot/dts/pxa910.dtsi

@@ -67,7 +67,7 @@ timer1: timer@d4016000 {
 				status = "disabled";
 			};
 
-			uart1: uart@d4017000 {
+			uart1: serial@d4017000 {
 				compatible = "mrvl,mmp-uart";
 				reg = <0xd4017000 0x1000>;
 				interrupts = <27>;
@@ -76,7 +76,7 @@ uart1: uart@d4017000 {
 				status = "disabled";
 			};
 
-			uart2: uart@d4018000 {
+			uart2: serial@d4018000 {
 				compatible = "mrvl,mmp-uart";
 				reg = <0xd4018000 0x1000>;
 				interrupts = <28>;
@@ -85,7 +85,7 @@ uart2: uart@d4018000 {
 				status = "disabled";
 			};
 
-			uart3: uart@d4036000 {
+			uart3: serial@d4036000 {
 				compatible = "mrvl,mmp-uart";
 				reg = <0xd4036000 0x1000>;
 				interrupts = <59>;