dpif-netdev: Free packets on TUNNEL_PUSH if should_steal.

dpif-netdev: Free packets on TUNNEL_PUSH if should_steal.

Unconditional return may cause packet leak in case of
'should_steal == true'.

Additionally, removed redundant checking for depth level.

CC: Sugesh Chandran <sugesh.chandran@intel.com>
Fixes: 7c12dfc527a5 ("tunneling: Avoid datapath-recirc by
                      combining recirc actions at xlate.")
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Ian Stokess <ian.stokes@intel.com>