tc_vlan: fix type of tcfv_push_vid

Should be u16. So fix it to kill the sparse warning.

Fixes: c7e2b968

 "sched: introduce vlan action"
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>