brcm2708: remove duplicated gzip from image generation

Images are now automatically gziped so remove custom image command

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

target/linux/brcm2708/image/Makefile

@@ -44,7 +44,6 @@ endef
 define Build/sdcard-img
 	./gen_rpi_sdcard_img.sh $@ $@.boot $(IMAGE_ROOTFS) \
 		$(CONFIG_BRCM2708_SD_BOOT_PARTSIZE) $(CONFIG_TARGET_ROOTFS_PARTSIZE)
-	$(if $(CONFIG_TARGET_IMAGES_GZIP),gzip -9n -c $@ > $(BIN_DIR)/$(notdir $@).gz)
 endef
 
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