IB/core: Remove ib_dma_*map_single_attrs()

Remove these functions because these are not used. Additionally, the
implementation of these functions is not correct for the hfi1, qib and
rxe drivers because dma_device is used instead of dma_ops.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>