it8213: PIO fixes (take 2)

* Rename it8213_tuneproc() to it8213_tune_pio() and add it8213_tuneproc()
  wrapper.  Move finding of the best PIO mode to the new wrapper.

* Add setting of transfer mode on the device to it8213_tuneproc().

* Don't call it8213_dma_2_pio() for PIO modes in it8213_tune_chipset().

* Use it8213_tuneproc() in it8213_config_drive_for_dma().

v2:
* Remove PIO modes from it8213_dma_2_pio(), they are no longer needed there
  (Noticed by Sergei)

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>