Low: fencer: allow peer configuration requests

34cb03a0 mistakenly disallowed fencing configuration requests made via peer CPG
(as opposed to client IPC, which is properly allowed or disallowed as
appropriate).

This has no practical effect since configuration requests are never made via
CPG (instead, the fencer loads configuration from CIB notifications, and the
executor makes client IPC requests for device starts and stops). However,
allowing them is more correct.