ARM: dts: uniphier: rename support card serial node to fix schema warning

Since commit e69f5dc6 ("dt-bindings: serial: Convert 8250 to
json-schema"), the schema for "ns16550a" is checked.

'make ARCH=arm dtbs_check' emits the following warning:

  uart@b0000: $nodename:0: 'uart@b0000' does not match '^serial(@[0-9a-f,]+)*$'

Rename the node to follow the pattern defined in
Documentation/devicetree/bindings/serial/serial.yaml
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/arm/boot/dts/uniphier-support-card.dtsi

@@ -23,7 +23,7 @@ ethsc: ethernet@0 {
 			reg-io-width = <4>;
 		};
 
-		serialsc: uart@b0000 {
+		serialsc: serial@b0000 {
 			compatible = "ns16550a";
 			reg = <0x000b0000 0x20>;
 			clock-frequency = <12288000>;