mac80211: minstrel: Change expected throughput unit back to Kbps

The change from cur_tp to the function
minstrel_get_tp_avg/minstrel_ht_get_tp_avg changed the unit used for the
current throughput. For example in minstrel_ht the correct
conversion between them would be:

    mrs->cur_tp / 10 == minstrel_ht_get_tp_avg(..).

This factor 10 must also be included in the calculation of
minstrel_get_expected_throughput and minstrel_ht_get_expected_throughput to
return values with the unit [Kbps] instead of [10Kbps]. Otherwise routing
algorithms like B.A.T.M.A.N. V will make incorrect decision based on these
values. Its kernel based implementation expects expected_throughput always
to have the unit [Kbps] and not sometimes [10Kbps] and sometimes [Kbps].

The same requirement has iw or olsrdv2's nl80211 based statistics module
which retrieve the same data via NL80211_STA_INFO_TX_BITRATE.

Cc: stable@vger.kernel.org
Fixes: 6a27b2c4

 ("mac80211: restructure per-rate throughput calculation into function")
Signed-off-by: Sven Eckelmann <sven@open-mesh.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>