In preparation to support other A20 based boards, rename the CUBIEBOARD2

kernel configuration to A20.

There are other boards (namely the banana pi) that use exactly the same
devices.

Additionally, we are moving from static FDT support (DTB compiled
in-kernel) to DTB passed to kernel by the boot loader (ubldr).  The u-boot
for these boards are already available on ports and as the crochet support
for these boards isn't committed yet, this should not bring any issues.

Discussed with:		ian

sys/arm/conf/A20

@@ -1,6 +1,5 @@
 #
-# CUBIEBOARD2 -- Custom configuration for the CUBIEBOARD2 ARM development
-# platform, check out http://www.cubieboard.org
+# A20 -- Custom configuration for the Allwinner A20 ARM SoC
 #
 # For more information on this file, please read the config(5) manual page,
 # and/or the handbook section on Kernel Configuration Files:
@@ -19,7 +18,7 @@
 #
 # $FreeBSD$
 
-ident		CUBIEBOARD2
+ident		A20
 
 include 	"std.armv6"
 include 	"../allwinner/a20/std.a20"
@@ -109,6 +108,4 @@ device		miibus
 
 # Flattened Device Tree
 options 	FDT			# Configure using FDT/DTB data
-options 	FDT_DTB_STATIC
-makeoptions	FDT_DTS_FILE=cubieboard2.dts
 makeoptions	MODULES_EXTRA=dtb/allwinner