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

adjusted to not touch unrelated devices

Signed-off-by: Alan Luck <luckyhome2008@gmail.com>
(cherry picked and adjusted from commit 4c0dc68f46)
Signed-off-by: Florian Maurer <f.maurer@outlook.de>

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 $@