ide-cd: remove ide_cd_drain_data and ide_cd_pad_transfer

Use the generic ide_pad_transfer() helper instead.

[bart: fixup ide_cd_drain_data() -> ide_pad_transfer() conversion]

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