Some devices have a really long power-on cycle, and we fail to
successfully probe these if they're plugged in and then turned on.

There's really no down-side to bumping the number of retries and the
retry delay, and most devices will get picked up within the first couple
of retries anyway.
Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>