ramips: add encrypted SGE factory image for D-Link devices

creates SGE encrypted factory images
to use via the D-Link web interface
rename the old factory unencrypted images to recovery
for use in the recovery console when recovery is needed
DIR-1935-A1 , DIR-853-A1 , DIR-853-A3 , DIR-867-A1 ,
DIR-878-A1 and DIR-882-A1

Signed-off-by: Alan Luck <luckyhome2008@gmail.com>

include/image-commands.mk

@@ -226,6 +226,11 @@ define Build/copy-file
 	cat "$(1)" > "$@"
 endef
 
+define Build/dlink-sge-image
+	$(STAGING_DIR_HOST)/bin/dlink-sge-image $(1) $@ $@.enc
+	mv $@.enc $@
+endef
+
 define Build/edimax-header
 	$(STAGING_DIR_HOST)/bin/mkedimaximg -i $@ -o $@.new $(1)
 	@mv $@.new $@