kconfig_lint: demote 'always defined' errors to warnings

To be able to run this as a lint-stable test, demote these to warnings
for now.  After the current CONFIG_MAINBOARD_POWER_ON_AFTER_POWER_FAIL
issues get fixed, these can be promoted again.

Change-Id: I1432980eb0c871fc61c12dcc351f8d46513a7965
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/13541
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/util/lint/kconfig_lint_README b/util/lint/kconfig_lint_README
index 3c638f5..5a5eacd 100644
--- a/util/lint/kconfig_lint_README
+++ b/util/lint/kconfig_lint_README
@@ -57,6 +57,8 @@
   symbols.
 - 'IS_ENABLED()' block that could not be interpreted.
 - Kconfig files that are not loaded by a 'source' keyword.
+- '#ifdef' or '#if defined' used on bool, int, or hex - these are always
+  defined in coreboot's version of Kconfig.
 
 Errors in Kconfig files:
 - Selects do not work on symbols created in a choice block.
@@ -89,8 +91,6 @@
 - Using a 'prompt' keyword not inside a config or choice block.
 
 Errors in coreboot source files:
-- '#ifdef' or '#if defined' used on bool, int, or hex - these are always
-  defined in coreboot's version of Kconfig.
 - The IS_ENABLED macro is only valid for bool symbols.
 - The IS_ENABLED used on unknown CONFIG_ value, like an obsolete symbol.
 - The IS_ENABLED macro is used on a symbol without the CONFIG_ prefix.