modem_diagnostics: add rules for getting battery info

Bug: 204961005
Change-Id: I07206955e7269c6732c47f8094ab50e622a8e6b0
diff --git a/vendor/google/modem_diagnostics.te b/vendor/google/modem_diagnostics.te
index 6783d1e..a01d3af 100644
--- a/vendor/google/modem_diagnostics.te
+++ b/vendor/google/modem_diagnostics.te
@@ -18,4 +18,7 @@
 
   set_prop(modem_diagnostic_app, vendor_modem_diag_prop)
   set_prop(modem_diagnostic_app, radio_control_prop)
+
+  allow modem_diagnostic_app sysfs_batteryinfo:file r_file_perms;
+  allow modem_diagnostic_app sysfs_batteryinfo:dir search;
 ')