checkpatch: kconfig: prefer 'help' over '---help---'

IMO, we should discourage '---help---' for new help texts, even in cases
where it would be consistent with other help texts in the file. This
will help if we ever want to get rid of '---help---' in the future.

Also simplify the code to only check for exactly '---help---'. Since
commit c2264564df3d ("kconfig: warn of unhandled characters in Kconfig
commands"), '---help---' is a proper keyword and can only appear in that
form. Prior to that commit, '---help---' working was more of a syntactic
quirk.

Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/checkpatch.pl

@@ -2817,7 +2817,11 @@ sub process {
 
 				if ($lines[$ln - 1] =~ /^\+\s*(?:bool|tristate|prompt)\s*["']/) {
 					$is_start = 1;
-				} elsif ($lines[$ln - 1] =~ /^\+\s*(?:---)?help(?:---)?$/) {
+				} elsif ($lines[$ln - 1] =~ /^\+\s*(?:help|---help---)\s*$/) {
+					if ($lines[$ln - 1] =~ "---help---") {
+						WARN("CONFIG_DESCRIPTION",
+						     "prefer 'help' over '---help---' for new help texts\n" . $herecurr);
+					}
 					$length = -1;
 				}