pktgen: multiqueue etc.

Sofar far pktgen have had a restriction to only use one device per kernel 
thread. With the new multiqueue architecture this is no longer adequate.

The patch below is an effort to remove this by in pktgen configuration 
adding a tag to  the device name a la eth0@0 etc. The tag is used for 
usual device config just as before. Also a new flag is introduced to mirror 
queue_map with sending threads smp_processor_id() QUEUE_MAP_CPU.

An example: We use 4 CPU's to send to one 10g interface (eth0)
 and we use the new tagging to send a mix of packet sizes, 64, 576 and
 1500 bytes. Also we use TX queues according to smp_processor_id()

 PGDEV=/proc/net/pktgen/kpktgend_0
 pgset "add_device eth0@0" 

 PGDEV=/proc/net/pktgen/kpktgend_1
 pgset "add_device eth0@1" 

 PGDEV=/proc/net/pktgen/kpktgend_2
 pgset "add_device eth0@2" 

 PGDEV=/proc/net/pktgen/kpktgend_3
 pgset "add_device eth0@3" 
....
PGDEV=/proc/net/pktgen/eth0@0 
pgset "pkt_size 64"
pgset "flag QUEUE_MAP_CPU"

PGDEV=/proc/net/pktgen/eth0@1
pgset "pkt_size 572"
pgset "flag QUEUE_MAP_CPU"

PGDEV=/proc/net/pktgen/eth0@2
pgset "pkt_size 1496"

PGDEV=/proc/net/pktgen/eth0@3
pgset "pkt_size 1496"
pgset "flag QUEUE_MAP_CPU"

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