fixed so that change of <resources> could be handled correctly.

In present code, whenever there is change of lrm_resources, re-registration of stonith device is performed.
Apr 16 14:37:29 [11075] vm01 stonith-ng: (      main.c:770   )    info: update_cib_stonith_devices_v2:  Updating device list from the cib: create lrm_resources

I think that it should be change of "resources" that update is originally performed.