ath79: qca953x: Add chosen node and specify console in bootargs

Most qca devices use 115200n8 as it's default uart baudrate.
Add 'chosen' node for qca953x like other SoCs in ath79 target.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>

target/linux/ath79/dts/qca9533.dtsi

@@ -8,6 +8,10 @@
 	#address-cells = <1>;
 	#size-cells = <1>;
 
+	chosen {
+		bootargs = "console=ttyS0,115200n8";
+	};
+
 	cpus {
 		#address-cells = <1>;
 		#size-cells = <0>;