[SCSI] qla2xxx: Use bitmap to store loop_id's for fcports.

Store used fcport loop_id's in a bitmap so that as opposed to looping through
all fcports to find the next free loop_id, new loop_id lookup can be just be
done via bitops.

[jejb: plus fix for incorrect LOOPID_MAP_SIZE from Andrew Vasquez]
Signed-off-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>