powerpc/fsl: update compatiable on fsl 16550 uart nodes

The Freescale serial port's are pretty much a 16550, however there are
some FSL specific bugs and features.  Add a "fsl,ns16550" compatiable
string to allow code to handle those FSL specific issues.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/boot/dts/kuroboxHG.dts b/arch/powerpc/boot/dts/kuroboxHG.dts
index b13a11e..0e758b3 100644
--- a/arch/powerpc/boot/dts/kuroboxHG.dts
+++ b/arch/powerpc/boot/dts/kuroboxHG.dts
@@ -84,7 +84,7 @@
 		serial0: serial@80004500 {
 			cell-index = <0>;
 			device_type = "serial";
-			compatible = "ns16550";
+			compatible = "fsl,ns16550", "ns16550";
 			reg = <0x80004500 0x8>;
 			clock-frequency = <130041000>;
 			current-speed = <9600>;
@@ -95,7 +95,7 @@
 		serial1: serial@80004600 {
 			cell-index = <1>;
 			device_type = "serial";
-			compatible = "ns16550";
+			compatible = "fsl,ns16550", "ns16550";
 			reg = <0x80004600 0x8>;
 			clock-frequency = <130041000>;
 			current-speed = <57600>;