[SCSI] scsi_dh_rdac: changes for rdac debug logging

Patch to add debugging stuff for rdac device handler.
- Added a bit mask "module parameter" rdac_logging with 2 bits for each type
  of logging.
- currently defined only two types of logging(failover and sense logging). Can
  be enhanced later if required.
- By default only failover logging is enabled which is equivalent of current
  logging.

Signed-off-by: Babu Moger <babu.moger@lsi.com>
Reviewed-by: Vijay Chauhan <vijay.chauhan@lsi.com>
Reviewed-by: Bob Stankey <Robert.stankey@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>