build: fix indent in image-commands.mk

Convert leading spaces to tab to match rest of the file.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
(cherry picked from commit 7e5a0da6426b3b14bde8798524826b64e16cf219)

include/image-commands.mk

@@ -120,7 +120,7 @@ define Build/append-uImage-fakehdr
 endef
 
 define Build/tplink-safeloader
-       -$(STAGING_DIR_HOST)/bin/tplink-safeloader \
+	-$(STAGING_DIR_HOST)/bin/tplink-safeloader \
 		-B $(TPLINK_BOARD_ID) \
 		-V $(REVISION) \
 		-k $(IMAGE_KERNEL) \