Allow radio access to netd_pid file.

They need to see when it changes so they know when netd bounces.

(cherrypicked from commit 71e9a7c4)

bug:18069270
Change-Id: I954cf43ff02f1d352015f128ef88b659e6d0f95a

radio.te

@@ -17,6 +17,9 @@ allow radio radio_data_file:notdevfile_class_set create_file_perms;
 
 allow radio alarm_device:chr_file rw_file_perms;
 
+allow radio net_data_file:dir search;
+allow radio net_data_file:file r_file_perms;
+
 # Property service
 allow radio radio_prop:property_service set;
 allow radio net_radio_prop:property_service set;