mac80211: mesh: drop frames appearing to be from us

[ Upstream commit 736a80bbfda709fb3631f5f62056f250a38e5804 ]

If there are multiple mesh stations with the same MAC address,
they will both get confused and start throwing warnings.

Obviously in this case nothing can actually work anyway, so just
drop frames that look like they're from ourselves early on.

Reported-by: Gui Iribarren <gui@altermundi.net>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>