[media] ds3000: clean up in tune procedure

Variable 'retune' does not make sense.
Loop is not needed for only one try.
Remove unnecessary dprintk's.
Remove a lot of debug messages and delays.
Signed-off-by: Igor M. Liplianin <liplianin@me.by>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>