Move HIDL interfaces not included in mainline_system.mk to system_ext

Test: aosp_wembley-userdebug
Bug: 161688072
Change-Id: If5f9419697bbd89d35dcd0220b1a80355835a3d1
diff --git a/radio/config/1.2/Android.bp b/radio/config/1.2/Android.bp
index 39d55ff..f751868 100644
--- a/radio/config/1.2/Android.bp
+++ b/radio/config/1.2/Android.bp
@@ -15,4 +15,5 @@
         "android.hidl.base@1.0",
     ],
     gen_java: true,
+    system_ext_specific: true,
 }