gemini: use common image prefix

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

SVN-Revision: 45782

target/linux/gemini/image/Makefile

@@ -76,7 +76,7 @@ define Image/Build
 	dd if=$(BIN_DIR)/$(IMG_PREFIX)-$(1).img of=$(BIN_DIR)/hddapp.tgz bs=6144k count=1 seek=1
 	cp $(BIN_DIR)/$(IMG_PREFIX)-nas4220-zImage $(BIN_DIR)/zImage
 	cp ./ImageInfo-ib4220 $(BIN_DIR)/ImageInfo
-	(cd $(BIN_DIR); tar -czf sysupgrade-ib4220.tar.gz ImageInfo zImage rd.gz hddapp.tgz)
+	(cd $(BIN_DIR); tar -czf $(IMG_PREFIX)-sysupgrade-ib4220.tar.gz ImageInfo zImage rd.gz hddapp.tgz)
 	mv $(BIN_DIR)/rd.gz $(BIN_DIR)/$(IMG_PREFIX)-nas4220-rd.gz
 	mv $(BIN_DIR)/hddapp.tgz $(BIN_DIR)/$(IMG_PREFIX)-nas4220-hddapp.tgz
 	rm -f $(BIN_DIR)/zImage $(BIN_DIR)/ImageInfo