IB/rxe, IB/rdmavt: Use dma_virt_ops instead of duplicating it

Make the rxe and rdmavt drivers use dma_virt_ops. Update the
comments that refer to the source files removed by this patch.
Remove struct ib_dma_mapping_ops. Remove ib_device.dma_ops.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Andrew Boyer <andrew.boyer@dell.com>
Cc: Dennis Dalessandro <dennis.dalessandro@intel.com>
Cc: Jonathan Toppins <jtoppins@redhat.com>
Cc: Alex Estrin <alex.estrin@intel.com>
Cc: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
index ace58ef..321cca6 100644
--- a/drivers/infiniband/sw/rxe/rxe_verbs.c
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
@@ -31,6 +31,7 @@
  * SOFTWARE.
  */
 
+#include <linux/dma-mapping.h>
 #include "rxe.h"
 #include "rxe_loc.h"
 #include "rxe_queue.h"
@@ -1235,7 +1236,7 @@ int rxe_register_device(struct rxe_dev *rxe)
 	dev->dev.parent = rxe_dma_device(rxe);
 	dev->local_dma_lkey = 0;
 	dev->node_guid = rxe_node_guid(rxe);
-	dev->dma_ops = &rxe_dma_mapping_ops;
+	dev->dev.dma_ops = &dma_virt_ops;
 
 	dev->uverbs_abi_ver = RXE_UVERBS_ABI_VERSION;
 	dev->uverbs_cmd_mask = BIT_ULL(IB_USER_VERBS_CMD_GET_CONTEXT)