QNX: Fix compiler warning by adding default return value

In static member function 'static QQnxAbstractVirtualKeyboard::EnterKeyType
QQnxAbstractVirtualKeyboard::qtEnterKeyTypeToQnx(Qt::EnterKeyType)':
warning: control reaches end of non-void function [-Wreturn-type]

Pick-to: 6.2 6.3
Task-number: QTBUG-101382
Change-Id: If3b0eda5d36257b0fbed54fb0a032c3b9d7ff989
Reviewed-by: James McDonnell <jmcdonnell@blackberry.com>

src/plugins/platforms/qnx/qqnxabstractvirtualkeyboard.cpp

@@ -149,6 +149,8 @@ QQnxAbstractVirtualKeyboard::EnterKeyType
     case Qt::EnterKeyPrevious: // unsupported
         return DefaultReturn;
     }
+    Q_UNREACHABLE();
+    return DefaultReturn;
 }
 
 QT_END_NAMESPACE