silence error for "invalid enum handover_scope value: none"

If no target cell got selected in a handover attempt, enum value NO_HANDOVER is
used. In that case, do not log a lot of errors saying
"invalid enum handover_scope value: none" -- they are misleading.

Change-Id: I98e748bea58ebb02812b6aaa6431c7d4b813242d
1 file changed