[PKTGEN]: Use kzalloc

These are cleanup patches for pktgen that can go in 2.6.15
Can use kzalloc in a couple of places.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Robert Olsson <robert.olsson@its.uu.se>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>