Fix free_cache to actually work

This broke with some other path-related changes, so it was scanning for
/data/*/cache instead of /data/data/*/cache

Also remove redundant call to restat

Bug: 5686310
Change-Id: Id1661f0f1337858fc9ead53c56ab7557f421c591

services/java/com/android/server/DeviceStorageMonitorService.java

@@ -163,7 +163,6 @@ public class DeviceStorageMonitorService extends Binder {
             } catch (IllegalArgumentException e) {
                 // ignore; report -1
             }
-            mCacheFileStats.restat(CACHE_PATH);
             EventLog.writeEvent(EventLogTags.FREE_STORAGE_LEFT,
                                 mFreeMem, mFreeSystem, mFreeCache);
         }