PCI: remove pci_dac_dma_... APIs on mn10300

It seems that mn10300 made it upstream after Jan Beulich's pci_dac_dma_*
cleanup work and still defines pci_dac_dma_supported(). This API is not
required by the PCI subsystem anymore, so remove it.

Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>