[AX25]: Use kmemdup

[AX25]: Use kmemdup

Code diff stats:

[acme@newtoy net-2.6.20]$ codiff /tmp/ax25.ko.before /tmp/ax25.ko.after
/pub/scm/linux/kernel/git/acme/net-2.6.20/net/ax25/ax25_out.c:
  ax25_send_frame |   -8
 1 function changed, 8 bytes removed

/pub/scm/linux/kernel/git/acme/net-2.6.20/net/ax25/ax25_route.c:
  ax25_rt_autobind |  -15
 1 function changed, 15 bytes removed

/pub/scm/linux/kernel/git/acme/net-2.6.20/net/ax25/af_ax25.c:
  ax25_make_new |  -33
 1 function changed, 33 bytes removed

/pub/scm/linux/kernel/git/acme/net-2.6.20/net/ax25/sysctl_net_ax25.c:
  ax25_register_sysctl |  -21
 1 function changed, 21 bytes removed

/tmp/ax25.ko.after:
 4 functions changed, 77 bytes removed
[acme@newtoy net-2.6.20]$

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>