[SCSI] add wrapper to access and set scsi_bus_type in struct acpi_bus_type

For being able to bind ata devices against acpi devices, scsi_bus_type
needs to be set as bus in struct acpi_bus_type. So add wrapper to
scsi_lib to accomplish that.

Signed-off-by: Holger Macht <holger@homac.de>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index f34a5a8..4527b3a 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -214,6 +214,16 @@
 		scsi_varlen_cdb_length(cmnd) : COMMAND_SIZE(cmnd[0]);
 }
 
+#ifdef CONFIG_ACPI
+struct acpi_bus_type;
+
+extern int
+scsi_register_acpi_bus_type(struct acpi_bus_type *bus);
+
+extern void
+scsi_unregister_acpi_bus_type(struct acpi_bus_type *bus);
+#endif
+
 /*
  *  SCSI Architecture Model (SAM) Status codes. Taken from SAM-3 draft
  *  T10/1561-D Revision 4 Draft dated 7th November 2002.