ARM: dts: consolidate aliases for Cygnus dt files

Move aliases into bcm-cygnus.dtsi to avoid duplications in Cygnus dts
files

Signed-off-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

arch/arm/boot/dts/bcm958305k.dts

@@ -38,10 +38,6 @@
 	model = "Cygnus Wireless Audio (BCM958305K)";
 	compatible = "brcm,bcm58305", "brcm,cygnus";
 
-	aliases {
-		serial0 = &uart3;
-	};
-
 	chosen {
 		stdout-path = &uart3;
 		bootargs = "console=ttyS0,115200";