fso-image.inc: do not search for .desktop files

fso-image.inc: do not search for .desktop files

We do not ship .desktop files in the image,so if we
  search for them we end up with this:
    ++ find ./usr/share/applications -name '*.desktop'
    find: `./usr/share/applications': No such file or directory
    + desktop=
  in do_rootfs and it fails.

So commenting that part fixes it

Thanks mickeyl for telling me(#openmoko-cdevel in Freenode)
  how to fix(so I didn't have to dig into it,and fixed quicker):
Apr 02 14:55:49 <mickeyl>       just comment this line out

PR was not bumped because for mickeyl told me(also #openmoko-cdevel in Freenode)
  that it was not necessary for images:
Apr 02 14:59:45 <GNUtoo>        should I INC_PR the file?
Apr 02 14:59:53 <mickeyl>       not necessary
Apr 02 14:59:59 <mickeyl>       image files will be reread
Apr 02 15:00:06 <mickeyl>       every time you build