checkpatch: allow parentheses on return for comparisons

It seems to be a common idiom to include braces on conditionals in all
contexts including return.  Allow this exception to the return is not a
function checks.  Reported by Kay Sievers.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -127,6 +127,7 @@ our $Lval	= qr{$Ident(?:$Member)*};
 
 our $Constant	= qr{(?:[0-9]+|0x[0-9a-fA-F]+)[UL]*};
 our $Assignment	= qr{(?:\*\=|/=|%=|\+=|-=|<<=|>>=|&=|\^=|\|=|=)};
+our $Compare    = qr{<=|>=|==|!=|<|>};
 our $Operators	= qr{
 			<=|>=|==|!=|
 			=>|->|<<|>>|<|>|!|~|
@@ -1983,9 +1984,9 @@ sub process {
 			my $spacing = $1;
 			my $value = $2;
 
-			# Flatten any parentheses and braces
+			# Flatten any parentheses
 			$value =~ s/\)\(/\) \(/g;
-			while ($value =~ s/\([^\(\)]*\)/1/) {
+			while ($value !~ /(?:$Ident|-?$Constant)\s*$Compare\s*(?:$Ident|-?$Constant)/ && $value =~ s/\([^\(\)]*\)/1/) {
 			}
 
 			if ($value =~ /^(?:$Ident|-?$Constant)$/) {