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 <zhouyanjie@cduestc.edu.cn>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips <linux-mips@vger.kernel.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Cc: devicetree@vger.kernel.org
Cc: robh+dt@kernel.org
Cc: ralf@linux-mips.org
Cc: jhogan@kernel.org
Cc: mark.rutland@arm.com
Cc: malat@debian.org
Cc: ezequiel@collabora.co.uk
Cc: ulf.hansson@linaro.org
Cc: syq <syq@debian.org>
Cc: jiaxun.yang <jiaxun.yang@flygoat.com>

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

@@ -76,7 +76,7 @@ &uart3 {
 	status = "okay";
 
 	pinctrl-names = "default";
-	pinctrl-0 = <&pins_uart2>;
+	pinctrl-0 = <&pins_uart3>;
 };
 
 &uart4 {
@@ -196,9 +196,9 @@ pins_uart1: uart1 {
 		bias-disable;
 	};
 
-	pins_uart2: uart2 {
-		function = "uart2";
-		groups = "uart2-data", "uart2-hwflow";
+	pins_uart3: uart3 {
+		function = "uart3";
+		groups = "uart3-data", "uart3-hwflow";
 		bias-disable;
 	};