lint: check for misuse of Kconfig SUBSYSTEM_*_ID

Check that nobody misuses the Kconfigs SUBSYSTEM_*_ID. They are meant to
be used for overriding the devicetree subsystem ids locally but shall
not be added to a board's Kconfig. Instead, the devicetree option
`subsystemid` should be used.

Add a linter script for this that finds and warns about such misuse.

Also add a note in the Kconfigs' description.

TEST=CB:45513

Change-Id: I21c021c718154f1396f795a555af47a76d6efe03
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45513
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

util/lint/lint-stable-024-kconfig-no-subsystem

@@ -0,0 +1,18 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# DESCR: Check that no board's Kconfig sets SUBSYSTEM_(VENDOR|DEVICE)_ID
+
+LC_ALL=C export LC_ALL
+FAIL=0
+
+for i in src/mainboard/*/* src/mainboard/*/*/variants/*; do
+  if [ -r $i/Kconfig ]; then
+    if grep -Eq "^\s*config\s+SUBSYSTEM_(VENDOR|DEVICE)_ID\>" $i/Kconfig; then
+      echo "$i: Mainboard sets SUBSYSTEM_*_ID. Set 'subsystemid' in devicetree instead!"
+      FAIL=1
+    fi
+  fi
+done
+
+exit $FAIL