ide: add ->read_status method

* Remove ide_read_status() inline helper.

* Add ->read_status method for reading ATA Status register
  and use it instead of ->INB.

While at it:

* Don't use HWGROUP() macro.

There should be no functional changes caused by this patch.

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