sfc: Use DMA_BIT_MASK() instead of our own DMA mask macros

Also change type of efx_nic_type::max_dma_mask to u64, matching
pci_dma_supported() parameter type.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index a84f975..77418ae 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -800,7 +800,7 @@
 	unsigned int txd_ring_mask;
 	unsigned int rxd_ring_mask;
 	unsigned int evq_size;
-	dma_addr_t max_dma_mask;
+	u64 max_dma_mask;
 	unsigned int tx_dma_mask;
 	unsigned bug5391_mask;