ath79: drop factory image for DIR-825 and TEW-673GRU

The max image sizes are too small to generate factory images.

Signed-off-by: Shiji Yang <[email protected]>

target/linux/ath79/image/generic.mk

@@ -1214,7 +1214,7 @@ define Device/dlink_dir-825-b1
 	kmod-leds-reset kmod-owl-loader kmod-switch-rtl8366s
   IMAGE_SIZE := 7808k
   FACTORY_SIZE := 6144k
-  IMAGES += factory.bin
+# IMAGES += factory.bin
   IMAGE/factory.bin = append-kernel | pad-to $$$$(BLOCKSIZE) | append-rootfs | \
 	pad-rootfs | check-size $$$$(FACTORY_SIZE) | pad-to $$$$(FACTORY_SIZE) | \
 	append-string 01AP94-AR7161-RT-080619-00
@@ -3030,7 +3030,7 @@ define Device/trendnet_tew-673gru
 	kmod-owl-loader kmod-switch-rtl8366s
   IMAGE_SIZE := 7808k
   FACTORY_SIZE := 6144k
-  IMAGES += factory.bin
+# IMAGES += factory.bin
   IMAGE/factory.bin = append-kernel | pad-to $$$$(BLOCKSIZE) | append-rootfs | \
 	pad-rootfs | check-size $$$$(FACTORY_SIZE) | pad-to $$$$(FACTORY_SIZE) | \
 	append-string AP94-AR7161-RT-080619-01