swupdate-progress: do not start psplash as default

If psplash is started on system headless can cause the board to hang or
slow dow. Do not start psplash as default.
Signed-off-by: Stefano Babic <sbabic@denx.de>

recipes-support/swupdate/swupdate/90-start-progress

-exec /usr/bin/swupdate-progress -w -p -r &
+exec /usr/bin/swupdate-progress -w -r &