Merge branch 'gretap-mirroring-selftests'

Petr Machata says:

====================
selftests: forwarding: Additions to mirror-to-gretap tests

This patchset is for a handful of edge cases in mirror-to-gretap
scenarios: removal of mirrored-to netdevice (#1), removal of underlay
route for tunnel remote endpoint (#2) and cessation of mirroring upon
removal of flower mirroring rule (#3).
====================

Signed-off-by: David S. Miller <davem@davemloft.net>