sbp2: misc debug logging cleanups

 - move call of scsi_print_command from sbp2_send_command to the beginning of
   sbp2_queue_command to show also commands which are not sent
 - put sbp2's name into scsi_print_sense
 - use __FUNCTION__ in log messages
 - remove a few less useful log messages and comments
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Jody McIntyre <scjody@modernduck.com>