r8169: use device model DMA API

Use DMA API as PCI equivalents will be deprecated. This change also
allow to allocate with GFP_KERNEL where possible.

Tested-by: Neal Becker <ndbecker2@gmail.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>