scsi: remove useless acpi functions in the header file

commit f1bc1e4c44 ("ata: acpi: rework the ata acpi bind support")
removed scsi_register_acpi_bus_type() and
scsi_unregister_acpi_bus_type(), but forgot to remove them in the header
file, do it now.

Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Reviewed-by: John Garry <john.garry@huawei.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

include/scsi/scsi.h

@@ -29,16 +29,6 @@ enum scsi_timeouts {
  */
 #define SCAN_WILD_CARD	~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_status_is_good - check the status return.
  *
  * @status: the status passed up from the driver (including host and