xfrm: Release dst if this dst is improper for vti tunnel

xfrm: Release dst if this dst is improper for vti tunnel

[ Upstream commit 236c9f84868534c718b6889aa624de64763281f9 ]

After searching rt by the vti tunnel dst/src parameter,
if this rt has neither attached to any transformation
nor the transformation is not tunnel oriented, this rt
should be released back to ip layer.

otherwise causing dst memory leakage.

Signed-off-by: Fan Du <fan.du@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>