net: Remove useless local var pkt

This has been pointless since commit 605d52e6, which was a
search-and-replace, overlooked the redundancy.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>