Revert "Use image-artifact-names"

This reverts commit ffa0420aaacab7014222ebad460bda4f91246ceb.

Signed-off-by: Stefano Babic <sbabic@denx.de>

classes/swupdate.bbclass

@@ -32,7 +32,6 @@
 #   image file with exactly the name as specified in SWUPDATE_IMAGES is searched for.
 
 inherit swupdate-common.bbclass
-inherit image-artifact-names
 
 S = "${WORKDIR}/${PN}"