Add sepolicy for contexthub HAL

Adding sepolicty for contexthub service.

Test: GTS tests pass.
Change-Id: I2576b8028d12a31151d7b7869679b853eb16c75e
diff --git a/public/hal_contexthub.te b/public/hal_contexthub.te
new file mode 100644
index 0000000..9d3685b
--- /dev/null
+++ b/public/hal_contexthub.te
@@ -0,0 +1,5 @@
+# hwbinder access
+hwbinder_use(hal_contexthub)
+
+# call into system_server process (callbacks)
+binder_call(hal_contexthub, system_server)