ide: remove CONFIG_IDEDMA_ONLYDISK

ATAPI devices with broken DMA support should be handled by DMA blacklist
and for debugging purposes we have new shiny "hdx=nodma" kernel paremeter.

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