hikey: Add support for contexthub hal and neonkey / argonkey sensor hal

Compile: make TARGET_SENSOR_MEZZANINE=<mezzanine_name>
         (<mezzanine_name> can be neonkey or argonkey)

Test: builds
Change-Id: I11c2734965b96cb34aef7558b7c822d0e5ea5c65
Signed-off-by: Ben Fennema <fennema@google.com>
diff --git a/sepolicy/property_contexts b/sepolicy/property_contexts
new file mode 100644
index 0000000..3a4bde3
--- /dev/null
+++ b/sepolicy/property_contexts
@@ -0,0 +1 @@
+sensors.                   u:object_r:sensors_prop:s0