modem_diagnostics: add rules for getting battery info

Bug: 204961005
Change-Id: Iaf92b2c0c71a34ad0e571f7298b59d3b9859d858
diff --git a/vendor/google/modem_diagnostics.te b/vendor/google/modem_diagnostics.te
index 4e7f3d5..c481738 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)
   set_prop(modem_diagnostic_app, vendor_radio_prop)
+
+  allow modem_diagnostic_app sysfs_batteryinfo:file r_file_perms;
+  allow modem_diagnostic_app sysfs_batteryinfo:dir search;
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