wpa_supplicant(hidl): Check for template conf files in /system

For older devices (like gce), the template conf files are kept in
/system instead of /vendor. So, check for the template file in both
/vendor & /system.

Also, since template path is the same for P2P & STA, removed that as a
param from |ensureConfigFileExists|.

Bug: 36645291
Test: Locally tested wifi enable on GCE
Test: Treehugger tests should pass now.

Change-Id: Ia1f94f327d1901fd2ef7a1c10a84e813cd9833a6
1 file changed