serial: fsl-imx-uart: Cleanup duplicate device tree binding

We had two bindings for the same serial device, it looks like the one in
tty/serial/fsl-imx-uart.txt is the more up to date one so go with it and
merge a few things about the use/need for aliases in from
serial/fsl-imx-uart.txt.
Signed-off-by: Kumar Gala <galak@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/fsl-imx-uart.txt

-* Freescale i.MX UART controller
-
-Required properties:
-- compatible : should be "fsl,imx21-uart"
-- reg : Address and length of the register set for the device
-- interrupts : Should contain UART interrupt number
-
-Optional properties:
-- fsl,uart-has-rtscts: indicate that RTS/CTS signals are used
-
-Note: Each uart controller should have an alias correctly numbered
-in "aliases" node.
-
-Example:
-
-- From imx51.dtsi:
-aliases {
-	serial0 = &uart1;
-	serial1 = &uart2;
-	serial2 = &uart3;
-};
-
-uart1: serial@73fbc000 {
-	compatible = "fsl,imx51-uart", "fsl,imx21-uart";
-	reg = <0x73fbc000 0x4000>;
-	interrupts = <31>;
-	status = "disabled";
-}
-
-- From imx51-babbage.dts:
-uart1: serial@73fbc000 {
-	fsl,uart-has-rtscts;
-	status = "okay";
-};
-

Documentation/devicetree/bindings/tty/serial/fsl-imx-uart.txt

@@ -11,9 +11,16 @@ Optional properties:
 - fsl,dte-mode : Indicate the uart works in DTE mode. The uart works
                   is DCE mode by default.
 
+Note: Each uart controller should have an alias correctly numbered
+in "aliases" node.
+
 Example:
 
-serial@73fbc000 {
+aliases {
+	serial0 = &uart1;
+};
+
+uart1: serial@73fbc000 {
 	compatible = "fsl,imx51-uart", "fsl,imx21-uart";
 	reg = <0x73fbc000 0x4000>;
 	interrupts = <31>;