xprtrdma: Clean up physical_op_map()

physical_op_unmap{_sync} don't use mr_nsegs, so don't bother to set
it in physical_op_map.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/physical_ops.c

@@ -68,7 +68,6 @@ physical_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
 	rpcrdma_map_one(ia->ri_device, seg, rpcrdma_data_dir(writing));
 	seg->mr_rkey = ia->ri_dma_mr->rkey;
 	seg->mr_base = seg->mr_dma;
-	seg->mr_nsegs = 1;
 	return 1;
 }