linux-wandboard

[NET]: Make helper to get dst entry and "use" it

There are many places that get the dst entry, increase the
__use counter and set the "lastuse" time stamp.

Make a helper for this.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>