mac80211: remove debug frame dumping

You can just pull up a monitor interface to get much more
detailed information, or, when debugging a driver, insert
dump code into the driver (which usually you will have to
do anyway to dump the driver-specific information). Hence
this option is useless.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>