ravb: Add nc_queue to struct ravb_hw_info

R-Car supports network control queue whereas RZ/G2L does not support
it. Add nc_queue to struct ravb_hw_info, so that NC queue is handled
only by R-Car.

This patch also renames ravb_rcar_dmac_init to ravb_dmac_init_rcar
to be consistent with the naming convention used in sh_eth driver.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>