ARM: dts: berlin: align UART node name with bindings

Bindings expect UART/serial node names to be "serial".

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

arch/arm/boot/dts/berlin2q.dtsi

···
 				status = "disabled";
 			};
 
-			uart0: uart@9000 {
+			uart0: serial@9000 {
 				compatible = "snps,dw-apb-uart";
 				reg = <0x9000 0x100>;
 				interrupts = <8>;
···
 				status = "disabled";
 			};
 
-			uart1: uart@a000 {
+			uart1: serial@a000 {
 				compatible = "snps,dw-apb-uart";
 				reg = <0xa000 0x100>;
 				interrupts = <9>;