mac80211: Remove superfluous ieee80211_rx_h_remove_qos_control

This seems to not serve any purpose anymore, at least all frame
processing afterwards seems to be able to deal with QoS frames. So,
let's save the expensive memmove and just leave the QoS header in the
802.11 frame for further processing.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>