[SCSI] scsi_dh_rdac : Add definitions for different RDAC operating modes

This patch adds definitions to support for different operating modes
for LSI rdac storage.  Currently, rdac support 3 operation modes.

1. RDAC mode(legacy)
2. AVT mode
3. IOSHIP mode

These definitions are used while activating the path(rdac_activate).

Signed-off-by: Babu Moger <babu.moger@lsi.com>
Reviewed-by: Yanling Qi <yanling.qi@lsi.com>
Reviewed-by: Sudhir Dachepalli <Sudhir.Dachepalli@lis.com>
Reviewed-by: Somasundaram Krishnasamy <Somasundaram.Krishnasamy@lsi.com>
Reviewed-by: Bob Stankey <Robert.Stankey@lsi.com>
Reviewed-by: Vijay Chauhan <Vijay.Chauhan@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>