mark the default WRT1900AC image "factory"

Signed-off-by: Imre Kaloz <kaloz@openwrt.org>

SVN-Revision: 41648

target/linux/mvebu/image/Makefile

@@ -48,7 +48,7 @@ define Image/Build/squashfs
 		dd if=$(KDIR)/uImage-armada-xp-mamba bs=3072k conv=sync; \
 		dd if=$(BIN_DIR)/$(IMG_PREFIX)-armada-xp-mamba-squashfs-ubinized.bin \
 		bs=2048 conv=sync; \
-	) > $(BIN_DIR)/$(IMG_PREFIX)-armada-xp-mamba-squashfs.img
+	) > $(BIN_DIR)/$(IMG_PREFIX)-armada-xp-mamba-squashfs-factory.img
 endef
 
 define Image/Build/Initramfs