[PATCH] cfg80211: Radiotap parser

Generic code to walk through the fields in a radiotap header, accounting
for nasties like extended "field present" bitfields and alignment rules

Signed-off-by: Andy Green <andy@warmcat.com>
Signed-off-by: Jiri Benc <jbenc@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>