[SCSI] qla4xxx: Complete the cmd if sense_len is zero

Complete the cmd if sense length is zero. For cases where sense
data spans across multiple iocb's by FW, we need to hold on to the
I/O (ha->status_srb != NULL) till we have processed them all and
copied the sense data from internal buffer to scsi_cmd sense buffer.

Signed-off-by: Prasanna Mumbai <prasanna.mumbai@qlogic.com>
Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <jbottomley@parallels.com>