Revert "build: scripts/config - update to kconfig-v5.6"

This reverts commit dcf3e63a35.

The kconfig update requires further testing and refinement until it can
remain in tree. Main problems are:

 - Recursive deps are now fatal instead of a warning
 - Previously legal syntax now leads to hard failures
 - It fails all package builds since multiple days

The updated kconfig implementation needs to cope with the current status
quo in the various package feeds before we can reconsider it for master.

It is not desirable that single broken packages can hard-fail the entire
build pipeline.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

scripts/config/qconf-cfg.sh

@@ -1,32 +0,0 @@
-#!/bin/sh
-# SPDX-License-Identifier: GPL-2.0
-
-PKG="Qt5Core Qt5Gui Qt5Widgets"
-PKG2="QtCore QtGui"
-
-if [ -z "$(command -v pkg-config)" ]; then
-	echo >&2 "*"
-	echo >&2 "* 'make xconfig' requires 'pkg-config'. Please install it."
-	echo >&2 "*"
-	exit 1
-fi
-
-if pkg-config --exists $PKG; then
-	echo cflags=\"-std=c++11 -fPIC $(pkg-config --cflags Qt5Core Qt5Gui Qt5Widgets)\"
-	echo libs=\"$(pkg-config --libs $PKG)\"
-	echo moc=\"$(pkg-config --variable=host_bins Qt5Core)/moc\"
-	exit 0
-fi
-
-if pkg-config --exists $PKG2; then
-	echo cflags=\"$(pkg-config --cflags $PKG2)\"
-	echo libs=\"$(pkg-config --libs $PKG2)\"
-	echo moc=\"$(pkg-config --variable=moc_location QtCore)\"
-	exit 0
-fi
-
-echo >&2 "*"
-echo >&2 "* Could not find Qt via pkg-config."
-echo >&2 "* Please install either Qt 4.8 or 5.x. and make sure it's in PKG_CONFIG_PATH"
-echo >&2 "*"
-exit 1