ide: add ide_no_data_taskfile() helper

* Add ide_no_data_taskfile() helper and convert ide_raw_taskfile() w/ NO DATA
  protocol users to use it instead.

* Set ->data_phase explicitly in ide_no_data_taskfile()
  (TASKFILE_NO_DATA is defined as 0x0000).

* Unexport task_no_data_intr().

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