change /fstab.* perms to 0640

It's safe to change the permissions on files in the root partitions;
incremental OTA now knows how to handle this case.

This reverts commit 08c370cc50e4bdae5a59f4ddfd1e3874bb36579d.

Change-Id: I503bf8ebd037fa9715494c6539e5430eee47acfe
diff --git a/include/private/android_filesystem_config.h b/include/private/android_filesystem_config.h
index 5b556d6..6521cbe 100644
--- a/include/private/android_filesystem_config.h
+++ b/include/private/android_filesystem_config.h
@@ -225,7 +225,7 @@
     { 00750, AID_ROOT,      AID_SHELL,     "init*" },
     { 00750, AID_ROOT,      AID_SHELL,     "charger*" },
     { 00750, AID_ROOT,      AID_SHELL,     "sbin/fs_mgr" },
-    { 00644, AID_ROOT,      AID_SHELL,     "fstab.*" },
+    { 00640, AID_ROOT,      AID_SHELL,     "fstab.*" },
     { 00644, AID_ROOT,      AID_ROOT,       0 },
 };