icside: fix ->speedproc to return on unsupported modes (take 5)

icside: fix ->speedproc to return on unsupported modes (take 5)

* All other implementations of ->speedproc return zero on success
  and non-zero on failure.  Currently it doesn't matter for icside host
  driver and isn't a bug per se since:

  - ide_set_xfer_rate() return value is ignored by all IDE core users

  - icside doesn't (yet!) use ide_tune_dma() in icside_dma_check()

  but sooner or later we will need to fix anyway - so lets do it now.

* icside_set_speed() happily accepts unsupported transfer modes which
  results in drive->drive_data being set to the maximum value (480)
  and drive->current_speed being set to the unsupported transfer mode.

  Fix it.

v2:
* The initial version of the patch was broken because it didn't take into
  the account (the different from usual) return values of icside_set_speed()
  (Noticed by Russell).

v3:
* Remove no longer needed initialization/checking of cycle_time
  (Noticed by Sergei).

* No need to set drive->drive_data if DMA is not going to be used
  (Noticed by Sergei).

* Remove incorrect setting of drive->current_speed
  (Noticed by Sergei).

* Move ide_config_drive_speed() at the end of icside_set_speed().

v4:
* If DMA mode is not found in icside_dma_check() then just return "-1" and
  don't call icside_set_speed() (v3 got it wrong and "1" was returned instead).

v5:
* Return "-1"/"0" in icside_set_speed() instead of icside_dma_check() return
  value (just like it was before this patch).

Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>