Android: Keyboard doesn't hide from done button

QLineEdit commits and hides QInputMethod on enter key press. When
Qt::ImhMultiLine input method hint is set, virtual keyboard is not
hidden.

Task-number: QTBUG-37850
Change-Id: I018351caa18bd2116665771e5f024a57182a01b9
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@theqtcompany.com>