wifi: mac80211: fix mesh path discovery based on unicast packets

If a packet has reached its intended destination, it was bumped to the code
that accepts it, without first checking if a mesh_path needs to be created
based on the discovered source.
Fix this by moving the destination address check further down.

Cc: stable@vger.kernel.org
Fixes: 986e43b1

 ("wifi: mac80211: fix receiving A-MSDU frames on mesh interfaces")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20230314095956.62085-3-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>