Fix QInputPanel::invokeAction(Click) not being called on mouse clicks

Fix QInputPanel::invokeAction(Click) not being called on mouse clicks

It appears that the introduction of the KeyRelease event type check in
commit 70cc5c9b7b420ecaf099d5d08fb1b4e8ad81a920 was accidential and meant
to use MouseButtonRelease (in QSGTextInputPrivate::sendMouseEventToInputContext).

This patch also removes the unnecessary QEvent::MouseMove check as well as
the mousePos = -1 setting if the position is out of range. The input methods
do the same check and reset() accordingly anyway.

Change-Id: Icf3638979583d97c066cb639f80fa11f44538d7c
Reviewed-by: Pekka Vuorela <pekka.ta.vuorela@nokia.com>
Reviewed-by: Andrew den Exter <andrew.den-exter@nokia.com>
Reviewed-by: Joona Petrell <joona.t.petrell@nokia.com>