PCI: Move pci_dma_* helpers to common code

For a long time all architectures implement the pci_dma_* functions using
the generic DMA API, and they all use the same header to do so.

Move this header, pci-dma-compat.h, to include/linux and include it from
the generic pci.h instead of having each arch duplicate this include.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

include/linux/pci.h

@@ -2011,4 +2011,8 @@ static inline bool pci_ari_enabled(struct pci_bus *bus)
 {
 	return bus->self && bus->self->ari_enabled;
 }
+
+/* provide the legacy pci_dma_* API */
+#include <linux/pci-dma-compat.h>
+
 #endif /* LINUX_PCI_H */