s4-common: add WiFi Direct support

* Add permissions: android.hardware.wifi.direct.xml
* Disable p2p in wpa_supplicant.conf so that p2p_supplicant.conf is used
  instead; this prevents network settings from being wiped out when WiFi
  Direct is used.
* Remove tdls_external_control=1; it was ripped from mako a while ago
  without any real justification.

Change-Id: I961de77b7e7c60a2e98d21f4acb72122c0f97613