Fix typos in QState sorting functions

Fix typos in QState sorting functions

A QObject can't be a child of itself, so the comparison always
returned false. In practice, this was causing the entry/exit order
of parallel states to be random.

QObject::children() is documented to contain the children in the
order in which they were added, so this fix actually achieves
deterministic behavior.

Task-number: QTBUG-25959
Change-Id: Id3f12d6bfbc249f1d4fed0bafb7d0217093e458e
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@nokia.com>