staging: rtl8723au: rtw_cfg80211_monitor_if_xmit_entry() use struct ieee80211_mgmt

Use struct ieee80211_mgmt to parse action frame. In addition remove
unused functions rtw_cfg80211_rx_p2p_action_public() and
rtw_cfg80211_rx_action_p2p()

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>