When a frame is transmitted via the nl80211 TX rather than as a
normal frame, IEEE80211_TX_CTRL_PORT_CTRL_PROTO wasn't set and
this will lead to wrong decisions (rate control etc.) being made
about the frame; fix this.

Fixes: 91180649 ("mac80211: Add support for tx_control_port")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20200326155333.f183f52b02f0.I4054e2a8c11c2ddcb795a0103c87be3538690243@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>