ide-floppy: merge idefloppy_{input,output}_buffers

We merge idefloppy_{input,output}_buffers() into idefloppy_io_buffers() by
introducing a 4th arg. called direction. According to its value
we atapi_input_bytes() or atapi_output_bytes(). Also, this simplifies the
interrupt handler logic a bit. Finally, rename idefloppy_io_buffers() to
ide_floppy_io_buffers().

Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>