pata_cs5520: remove dead VDMA support

It has been dead for the last three years (== since the initial driver
merge) and probability that it will ever get fixed is quite low.

Since there is no reason to keep this dead code around any longer just
remove it (it can still be retrieved from the git history if necessary).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>