Wifi: Add SePolicy for wifi_ext

This commit adds the SePolicy for wifi_ext hal service.

Bug: 149241184
Test: $ adb shell lshal | grep wifi_ext
        DM    Y vendor.google.wifi_ext@1.0::IWifiExt/default 0/1        979    2358 666
        DM,FC Y vendor.google.wifi_ext@1.1::IWifiExt/default 0/1        979    2358 666
Change-Id: I7ecf2f6277d25d4050deaa17b1019e3acb3fc09d
diff --git a/wifi_ext/hwservice_contexts b/wifi_ext/hwservice_contexts
new file mode 100644
index 0000000..e8de4ce
--- /dev/null
+++ b/wifi_ext/hwservice_contexts
@@ -0,0 +1,2 @@
+# Wifi
+vendor.google.wifi_ext::IWifiExt                                u:object_r:hal_wifi_ext_hwservice:s0