alim15x3: PIO mode setup fixes

* Return failure in ->speedproc method for unsupported/invalid transfer
  modes passed from user-space (fixes theoretical OOPS in ali_tune_pio()
  and/or setting random PIO timings on host controller + disabling UDMA
  bit + setting unsupported/invalid transfer mode on the device).

* Don't disable UDMA bit when programming PIO modes.

* Add FIXME about DMA timings never being set.

* Bump driver version.

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