[SCSI] qla2xxx: Correct vp_idx checking during PORT_UPDATE processing.

Checks should only be done for NPIV-capable ISPs.  Original code
could result in PORT_UPDATEs being missed on non-NPIV-capable
ISPs.

Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>