axolotl: cleanup CNE and DPM properties

  - Move CNE properties from system.prop to vendor.prop
  - Create system_ext.prop and add DPM properties

Change-Id: I55cd5e65521054e5af394b152cd04bd9d20c3a4d
Signed-off-by: Alexander Martinz <amartinz@shiftphones.com>
diff --git a/vendor.prop b/vendor.prop
index 4260a48..3d35b2c 100644
--- a/vendor.prop
+++ b/vendor.prop
@@ -111,6 +111,9 @@
 # CHRE
 vendor.chre.enabled=0
 
+# CNE
+persist.vendor.cne.feature=1
+
 # Disable SPU
 vendor.gatekeeper.disable_spu=true