Do not mark any touch points as primary when no mouse event is sent

The touchscreen plug-in generates touch events only and therefore no
touch point must be marked as primary because that would mean there
is also a mouse event created from that point which is not the case.

Change-Id: I80c5fdbc52b048cd74c834900b6c8100963210e6
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

src/plugins/generic/touchscreen/qtouchscreen.cpp

@@ -247,10 +247,6 @@ void QTouchScreenData::processInputEvent(input_event *data)
         if (key == -1)
             key = m_contacts.count();
 
-        // Mark the first point as primary.
-        if (m_contacts.isEmpty())
-            m_currentData.flags |= QTouchEvent::TouchPoint::Primary;
-
         m_contacts.insert(key, m_currentData);
         m_currentData = Contact();