[media] dib0700: add a sleep before attempting to detect dib7000p

Add a sleep since in some cases the dib7000p wasn't online when being probed.
The optimal timing has not yet been determined.

Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Cc: Patrick Boettcher <pboettcher@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>