ide: add ide_io_buffers() helper

* Make ->io_buffers method return number of bytes transferred.

* Use ide_end_request() instead of idefloppy_end_request()
  in ide_floppy_io_buffers() and then move the call out to
  ide_pc_intr().

* Add ide_io_buffers() helper and convert ide-{floppy,scsi}.c
  to use it instead of ide*_io_buffers().

There should be no functional changes caused by this patch.

Acked-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-tape.c

@@ -693,13 +693,15 @@ static void ide_tape_handle_dsc(ide_drive_t *drive)
 	idetape_postpone_request(drive);
 }
 
-static void ide_tape_io_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
+static int ide_tape_io_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
 				unsigned int bcount, int write)
 {
 	if (write)
 		idetape_output_buffers(drive, pc, bcount);
 	else
 		idetape_input_buffers(drive, pc, bcount);
+
+	return bcount;
 }
 
 /*