avr32: add generic board support

Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/arch/avr32/lib/Makefile b/arch/avr32/lib/Makefile
index 5f2d97b..6750913 100644
--- a/arch/avr32/lib/Makefile
+++ b/arch/avr32/lib/Makefile
@@ -8,7 +8,9 @@
 #
 
 obj-y	+= memset.o
+ifndef CONFIG_SYS_GENERIC_BOARD
 obj-y	+= board.o
+endif
 obj-$(CONFIG_CMD_BOOTM) += bootm.o
 obj-y	+= interrupts.o
 obj-y	+= dram_init.o