[SCSI] bfa: IOC fixes, check for IOC down condition.

Currently BFA was not checking for IOC down condition when issuing
getstats/clearstats

Add check to see if IOC is operational, before issuing
getstats/clearstats.

Signed-off-by: Krishna Gudipati <kgudipat@brocade.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>