scripts: checkpatch: allow "case" macros

Do not report errors like below:

./scripts/checkpatch.pl -f drivers/net/wireless/ath/ath10k/wmi.h

ERROR: Macros with complex values should be enclosed in parentheses
+#define C2S(x) case x: return #x

since many "case ..." macros are already used by some in-kernel drivers.

Link: https://lkml.kernel.org/r/20221027134334.164301-1-stf_xl@wp.pl
Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
Acked-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

scripts/checkpatch.pl

@@ -5918,6 +5918,7 @@ sub process {
 			    $dstat !~ /$exceptions/ &&
 			    $dstat !~ /^\.$Ident\s*=/ &&				# .foo =
 			    $dstat !~ /^(?:\#\s*$Ident|\#\s*$Constant)\s*$/ &&		# stringification #foo
+			    $dstat !~ /^case\b/ &&					# case ...
 			    $dstat !~ /^do\s*$Constant\s*while\s*$Constant;?$/ &&	# do {...} while (...); // do {...} while (...)
 			    $dstat !~ /^while\s*$Constant\s*$Constant\s*$/ &&		# while (...) {...}
 			    $dstat !~ /^for\s*$Constant$/ &&				# for (...)