IB/core: Remove ib_device.dma_device

Add code in ib_register_device() for copying the DMA masks. Use
&ib_device.dev in DMA mapping operations instead of dma_device.
Remove ib_device.dma_device because due to this and previous patches
it is no longer used.

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