mac80211: remove redundant check

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
Revert "mac80211: mesh: pick cheapest mpath among all interfaces"

This reverts commit 89eb2e29bbf5c2ff7579b23c63055552b68c0f87.

It wasn't possible to add more than one mpath for a given
(sdata, DA) pair, and mesh_assign_nexthop() will update
the mpath if a better metric was found anyway.

Conflicts:
	net/mac80211/mesh_pathtbl.c

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>