swupdate_class: multiple type extensions for images
swupdate_class: multiple type extensions for images

There is an issue adding kernel image, that share the same name,
for example uImage-<machine>.dtb and uImage-<machine>.bin, and both
are notpicked up into the .swu image. This allows to select
multiple file extensions, and both kernel and dtb file are
added to the compound image.

Signed-off-by: Stefano Babic <2c2905e0c2877c7e4ce40c7425e972302953fda5@denx.de>

sbabic/meta-swupdate,sbabic/meta-swupdate