[SCSI] fnic: Hitting BUG_ON(io_req->abts_done) in fnic_rport_exch_reset

Hitting BUG_ON(io_req->abts_done) in fnic_rport_exch_reset in case of
timing issue and also to some extent locking issue where abts and terminate
is happening around same timing.

The code changes are intended to update CMD_STATE(sc) and
io_req->abts_done together.

Signed-off-by: Sesidhar Beddel <sebaddel@cisco.com>
Signed-off-by: Hiral Patel <hiralpat@cisco.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>