mac80211: fix timing for 5 MHz and 10 MHz channels

according to IEEE 802.11-2012 section 18, various timings change
when using 5 MHz and 10 MHz. Reflect this by using a "shift" when
calculating durations.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

diff --cc net/mac80211/ieee80211_i.h
Simple merge

diff --cc net/mac80211/rc80211_minstrel.c
Simple merge

diff --cc net/mac80211/rc80211_minstrel_ht.c
Simple merge

diff --cc net/mac80211/tx.c
Simple merge

diff --cc net/mac80211/util.c
Simple merge