scsi: fdomain: use BSTAT_{MSG|CMD|IO} in fdomain_work()

Commit 1697c6a6 ("scsi: fdomain: Add register definitions") somehow
missed the masking of the 'status' variable with the SCSI phase mask in
fdomain_work(), leaving the magic number intact. Fix this issue; while at
it, change the order of BSTAT_{MSG|CMD|IO} bits in the MESSAGE IN
phase *case* (with no change in the generated object file).

Fixes: 1697c6a6 ("scsi: fdomain: Add register definitions")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>