sis5513: PIO mode setup fixes

* limit max PIO mode to PIO4, this driver doesn't support PIO5 and attempt
  to program PIO5 by config_art_rwp_pio() could result in incorrect PIO
  timings being programmed and possibly the data corruption (for < ATA100
  family chipsets PIO0 timings were used, for ATA100 and ATA100a - the random
  content of test1 variable was used, for ATA133 - MWDMA0 timings were used)

* BUG() in sis5513_tune_chipset() if somebody tries to force unsupported PIO5,
  also cleanup this function a bit while at it

* add comment about PIO0 timings for < ATA100 family chipsets

* remove open-coded best PIO mode selection from config_art_rwp_pio(),
  it contained numerous bugs:

  - it didn't check for validity of id->eide_pio_modes and id->eide_pio_iordy
    before using them

  - it tried to found out maximum PIO mode basing on minimum IORDY cycle time
    (moreover wrong cycle times were used for PIO1/5)

  - it was overriding PIO blacklist and conservative PIO "downgrade" done
    by ide_get_best_pio_mode()

* use sis5513_tune_drive() instead of config_art_rwp_pio()
  in sis5513_config_xfer_rate() so the correct PIO mode is also set
  on drive even if the device is not IORDY/DMA capable

* config_art_rwp_pio() was always setting the best possible mode and not
  the wanted one - fix it and move ide_get_best_pio_mode() call to
  config_chipset_for_pio()

* don't use ide_find_best_mode() in config_chipset_for_pio(), it was being
  overriden by config_art_rwp_pio() for the host timings anyway + we need to
  set the same PIO mode on the device and the host

* pass correct "pio" argument (255 instead of 5) to sis5513_tune_drive() call
  in sis5513_config_xfer_rate() so the best PIO mode is set on the drive
  and not PIO4

* rename sis5513_tune_drive() to sis5513_tuneproc()
  and config_chipset_for_pio() to sis5513_tune_driver()

* bump driver version

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>