mac80211: fix basic rate bitmap calculation

mac80211: fix basic rate bitmap calculation

upstream commit: 7e0986c17f695952ce5d61ed793ce048ba90a661

"mac80211: fix basic rates setting from association response"
introduced a copy/paste error.

Unfortunately, this not just leads to wrong data being passed
to the driver but is remotely exploitable for some hardware or
driver combinations.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>