DTS: CI20: Fix bugs in ci20's device tree.

According to the Schematic, the hardware of ci20 leads to uart3,
but not to uart2. Uart2 is miswritten in the original code.

Signed-off-by: Zhou Yanjie <[e-mail]>
Signed-off-by: Paul Burton <[e-mail]>
Cc: linux-mips <[e-mail]>
Cc: linux-kernel <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: syq <[e-mail]>
Cc: jiaxun.yang <[e-mail]>

arch/mips/boot/dts/ingenic/ci20.dts

···
 	status = "okay";
 
 	pinctrl-names = "default";
-	pinctrl-0 = <&pins_uart2>;
+	pinctrl-0 = <&pins_uart3>;
 };
 
 &uart4 {
···
 		bias-disable;
 	};
 
-	pins_uart2: uart2 {
-		function = "uart2";
-		groups = "uart2-data", "uart2-hwflow";
+	pins_uart3: uart3 {
+		function = "uart3";
+		groups = "uart3-data", "uart3-hwflow";
 		bias-disable;
 	};