[SCSI] bfa: Handle SCSI IO underrun case.

When IO is completed with underrun and with good SCSI status, check if
the transferred bytes against scsi_cmnd->underflow, which is set to
minimum number of bytes that must be transferred for this command, if
is less than required minimum, complete the IO with DID_ERROR.

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