mac80211: don't clear next_hop in path reclaim

Luis pointed out that this path is going to be freed right
away anyway so there's no point in assigning next_hop.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Luis Carlos Cobo <luisca@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>