b43: Pass more RX flags to mac80211

This changes the RX handler to pass more status flags to mac80211.
It also changes part of the drop policy, if bad frames were requested. (Note that
currently mac80211 will throw a WARN_ON in that case. But nothing bad will happen).

This also removes some obsolete unused timestamping code.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>