pktgen node allocation

Here is patch to manipulate packet node allocation and implicitly
how packets are DMA'd etc.

The flag NODE_ALLOC enables the function and numa_node_id();
when enabled it can also be explicitly controlled via a new
node parameter

Tested this with 10 Intel 82599 ports w. TYAN S7025 E5520 CPU's.
Was able to TX/DMA ~80 Gbit/s to Ethernet wires.

Signed-off-by: Robert Olsson <robert.olsson@its.uu.se>
Signed-off-by: David S. Miller <davem@davemloft.net>