Tinker Board add RTS uart0

Allow the possiblity of loading bluetooth.

Special thanks to @Miouyouyou for following up on this

to test:
--------------------------------------
cd /sys/class/gpio
echo 146 > export
echo 149 > export
echo 151 > export
echo high > gpio146/direction
echo high > gpio149/direction
echo high > gpio151/direction

----------------------------------------
clone/build/acquire:

https://github.com/lwfinger/rtl8723bs_bt

then execute:

./rtk_hciattach -n -s 115200 /dev/ttyS0 rtk_h5

patch/kernel/rockchip-next/2028-Tinker-Bluetooth.patch

@@ -0,0 +1,30 @@
+diff --git a/arch/arm/boot/dts/rk3288-tinker.dts b/arch/arm/boot/dts/rk3288-tinker.dts
+index 07b4af4..7755426 100644
+--- a/arch/arm/boot/dts/rk3288-tinker.dts
++++ b/arch/arm/boot/dts/rk3288-tinker.dts
+@@ -162,7 +162,7 @@
+ 		WIFI,host_wake_irq = <&gpio4 30 GPIO_ACTIVE_HIGH>;
+ 		status = "okay";
+ 	};
+-
++/*
+ 	wireless-bluetooth {
+ 		compatible = "bluetooth-platdata";
+ 		uart_rts_gpios = <&gpio4 19 GPIO_ACTIVE_LOW>;
+@@ -174,6 +174,7 @@
+ 		BT,wake_host_irq = <&gpio4 31 GPIO_ACTIVE_HIGH>;
+ 		status = "okay";
+ 	};
++*/
+
+ };
+
+@@ -620,7 +621,7 @@
+ &uart0 {
+ 	status = "okay";
+ 	pinctrl-names = "default";
+-	pinctrl-0 = <&uart0_xfer>, <&uart0_cts>;
++	pinctrl-0 = <&uart0_xfer>, <&uart0_cts>,  <&uart0_rts>;
+ };
+
+ &uart1 {