build: remove image specific checksum code

Now that we globally calculate sha256sums over the bin/ directory we can remove
the target image specific checksum handling.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

include/image.mk

@@ -265,12 +265,6 @@ define Image/mkfs/prepare
 endef
 
 
-define Image/Checksum
-	( cd ${BIN_DIR} ; \
-		$(FIND) -maxdepth 1 -type f \! -name 'md5sums'  -printf "%P\n" | sort | xargs $1 > $2 \
-	)
-endef
-
 ifdef CONFIG_TARGET_ROOTFS_TARGZ
   define Image/Build/targz
 	$(TAR) -cp --numeric-owner --owner=0 --group=0 --sort=name \
@@ -569,7 +563,5 @@ define BuildImage
 	$(MAKE) legacy-images
 
   install: install-images
-	$(call Image/Checksum,md5sum --binary,md5sums)
-	$(call Image/Checksum,openssl dgst -sha256,sha256sums)
 
 endef