this warning:

  net/sunrpc/xprtrdma/svc_rdma_transport.c: In function ‘svc_rdma_accept’:
  net/sunrpc/xprtrdma/svc_rdma_transport.c:830: warning: ‘dma_mr_acc’ may be used uninitialized in this function

triggers because GCC does not recognize the (correct) flow connection
between need_dma_mr and dma_mr_acc.

Annotate it.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>