[SCSI] qla2xxx: Clear drive active CRB register when not in use.

The CRB drive active register is cleared when driver is unloaded
or when driver enters failed state.

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