[SCSI] add ability to deny binding to SPI transport class

This patch is necessary if we begin exposing underlying physical disks
(which can attach to the SPI transport class) of the hardware RAID
cards, since we don't want any SPI parameters binding to the RAID
devices.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/include/scsi/scsi_transport_spi.h b/include/scsi/scsi_transport_spi.h
index d8ef860..6bdc4af 100644
--- a/include/scsi/scsi_transport_spi.h
+++ b/include/scsi/scsi_transport_spi.h
@@ -120,6 +120,7 @@
 	void	(*set_hold_mcs)(struct scsi_target *, int);
 	void	(*get_signalling)(struct Scsi_Host *);
 	void	(*set_signalling)(struct Scsi_Host *, enum spi_signal_type);
+	int	(*deny_binding)(struct scsi_target *);
 	/* The driver sets these to tell the transport class it
 	 * wants the attributes displayed in sysfs.  If the show_ flag
 	 * is not set, the attribute will be private to the transport