swupdate-image: rm image-artifact-names in dunfell
The swupdate-image class in the dunfell branch inherited an
image-artifact-names class from oe-core/meta master, which does *not*
exist in the oe-core branch for dunfell. As the inherit is not even
needed, remove it.
Note: this does not change master, only dunfell.
Signed-off-by: Olaf Mandel <o.mandel@menlosystems.com>
Acked-by: Stefano Babic <sbabic@denx.de>