ide: add ide_transfer_pc() helper

* Add ide-atapi.c file for generic ATAPI support together with
  CONFIG_IDE_ATAPI config option.

* Add generic ide_transfer_pc() helper to ide-atapi.c and then
  convert ide-{floppy,tape,scsi} device drivers to use it.

There should be no functional changes caused by this patch.

Cc: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/include/linux/ide.h b/include/linux/ide.h
index 89feaea..bed3c58 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -967,6 +967,9 @@
 
 void ide_pktcmd_tf_load(ide_drive_t *, u32, u16, u8);
 
+ide_startstop_t ide_transfer_pc(ide_drive_t *, struct ide_atapi_pc *,
+				ide_handler_t *, unsigned int, ide_expiry_t *);
+
 ide_startstop_t do_rw_taskfile(ide_drive_t *, ide_task_t *);
 
 void task_end_request(ide_drive_t *, struct request *, u8);