ide: remove atapi_feature_t

Remove atapi_feature_t.

While at it:
* replace 'HWIF(drive)' by 'hwif'

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