libata: remove no longer needed pata_winbond driver

Winbond W83759A controller is fully supported by pata_legacy driver
so remove no longer needed pata_winbond driver.

Leave PATA_WINBOND_VLB config option for compatibility reasons
and teach pata_legacy to preserve the old behavior of pata_winbond
driver.

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