multipath: retry the DID_SOFT_ERROR for rdac checker commands

multipath: retry the DID_SOFT_ERROR for rdac checker commands

Sometimes we have seen immediate path failures for DID_SOFT_ERROR status. Just add a retry as other statuses.
It will basically add 5 retries.

Here are the messages.
Jun  4 17:46:42 ictc-billy kernel: mpt2sas0: log_info(0x31120100): originator(PL), code(0x12), sub_code(0x0100)
Jun  4 17:46:42 ictc-billy kernel: sd 1:0:0:47: [sdn] Unhandled error code
Jun  4 17:46:42 ictc-billy kernel: sd 1:0:0:47: [sdn] Result: hostbyte=DID_SOFT_ERROR driverbyte=DRIVER_OK
Jun  4 17:46:42 ictc-billy kernel: sd 1:0:0:47: [sdn] CDB: Write(10): 2a 00 00 06 e4 a0 00 00 20 00
Jun  4 17:46:42 ictc-billy kernel: device-mapper: multipath: Failing path 8:208.
Jun  4 17:46:42 ictc-billy multipathd: 8:208: mark as failed
Jun  4 17:46:42 ictc-billy multipathd: mpathat: remaining active paths: 1

Signed-off-by: Babu Moger <babu.moger@netapp.com>