raspberrypi: enable dual HDMI output for RPi4

Add configuration to config.txt to enable both HDMI outputs.
The KMS atomic API needs to be disabled as it fails with
dual HDMI output.

Taskk-number: QTBUG-82816
Change-Id: I1a9cc95eecd9fad253862da764f52bebb5cdd1df
Reviewed-by: Mikko Gronoff <mikko.gronoff@qt.io>

meta-boot2qt-distro/dynamic-layers/raspberrypi/recipes-bsp/bootfiles/rpi-config_git.bbappend

+############################################################################
+##
+## Copyright (C) 2020 The Qt Company Ltd.
+## Contact: https://www.qt.io/licensing/
+##
+## This file is part of the Boot to Qt meta layer.
+##
+## $QT_BEGIN_LICENSE:GPL$
+## Commercial License Usage
+## Licensees holding valid commercial Qt licenses may use this file in
+## accordance with the commercial license agreement provided with the
+## Software or, alternatively, in accordance with the terms contained in
+## a written agreement between you and The Qt Company. For licensing terms
+## and conditions see https://www.qt.io/terms-conditions. For further
+## information use the contact form at https://www.qt.io/contact-us.
+##
+## GNU General Public License Usage
+## Alternatively, this file may be used under the terms of the GNU
+## General Public License version 3 or (at your option) any later version
+## approved by the KDE Free Qt Foundation. The licenses are as published by
+## the Free Software Foundation and appearing in the file LICENSE.GPL3
+## included in the packaging of this file. Please review the following
+## information to ensure the GNU General Public License requirements will
+## be met: https://www.gnu.org/licenses/gpl-3.0.html.
+##
+## $QT_END_LICENSE$
+##
+############################################################################
+
+do_deploy_append_raspberrypi4() {
+    echo "# enable both hdmi outputs" >> ${DEPLOYDIR}/bcm2835-bootfiles/config.txt
+    echo "max_framebuffers=2" >> ${DEPLOYDIR}/bcm2835-bootfiles/config.txt
+}

meta-boot2qt-distro/dynamic-layers/raspberrypi/recipes-qt/boot2qt-addons/default-qt-envs.bbappend

@@ -29,5 +29,5 @@
 
 do_configure_append() {
     echo "QT_QPA_EGLFS_FORCE888=1" >> ${WORKDIR}/defaults
-    echo "QT_QPA_EGLFS_KMS_ATOMIC=1" >> ${WORKDIR}/defaults
+    echo "QT_QPA_EGLFS_KMS_ATOMIC=0" >> ${WORKDIR}/defaults
 }