checkpatch: always parse orig_commit in fixes tag

Do not require the presence of `$balanced_parens` to get the commit SHA;
this allows a `Fixes: deadbeef` tag to get a correct suggestion rather
than a suggestion containing a reference to HEAD.

Given this patch:

: From: Tamir Duberstein <[email protected]>
: Subject: Test patch
: Date: Fri, 25 Oct 2024 19:30:51 -0400
: 
: This is a test patch.
: 
: Fixes: bd17e03
: Signed-off-by: Tamir Duberstein <[email protected]>
: --- /dev/null
: +++ b/new-file
: @@ -0,0 +1 @@
: +Test.


Before:

WARNING: Please use correct Fixes: style 'Fixes: <12 chars of sha1> ("<title line>")' - ie: 'Fixes: c10a7d25e68f ("Test patch")'

After:

WARNING: Please use correct Fixes: style 'Fixes: <12 chars of sha1> ("<title line>")' - ie: 'Fixes: bd17e03 ("checkpatch: warn for non-standard fixes tag style")'



The prior behavior incorrectly suggested the patch's own SHA and title
line rather than the referenced commit's.  This fixes that.

Ironically this:

Fixes: bd17e03 ("checkpatch: warn for non-standard fixes tag style")
Signed-off-by: Tamir Duberstein <[email protected]>
Cc: Andy Whitcroft <[email protected]>
Cc: Dwaipayan Ray <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Louis Peens <[email protected]>
Cc: Lukas Bulwahn <[email protected]>
Cc: Niklas Söderlund <[email protected]>
Cc: Philippe Schenker <[email protected]>
Cc: Simon Horman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

scripts/checkpatch.pl

@@ -3209,36 +3209,31 @@ sub process {
 
 # Check Fixes: styles is correct
 		if (!$in_header_lines &&
-		    $line =~ /^\s*fixes:?\s*(?:commit\s*)?[0-9a-f]{5,}\b/i) {
-			my $orig_commit = "";
-			my $id = "0123456789ab";
-			my $title = "commit title";
-			my $tag_case = 1;
-			my $tag_space = 1;
-			my $id_length = 1;
-			my $id_case = 1;
+		    $line =~ /^\s*(fixes:?)\s*(?:commit\s*)?([0-9a-f]{5,40})(?:\s*($balanced_parens))?/i) {
+			my $tag = $1;
+			my $orig_commit = $2;
+			my $title;
 			my $title_has_quotes = 0;
 			$fixes_tag = 1;
-
-			if ($line =~ /(\s*fixes:?)\s+([0-9a-f]{5,})\s+($balanced_parens)/i) {
-				my $tag = $1;
-				$orig_commit = $2;
-				$title = $3;
-
-				$tag_case = 0 if $tag eq "Fixes:";
-				$tag_space = 0 if ($line =~ /^fixes:? [0-9a-f]{5,} ($balanced_parens)/i);
-
-				$id_length = 0 if ($orig_commit =~ /^[0-9a-f]{12}$/i);
-				$id_case = 0 if ($orig_commit !~ /[A-F]/);
-
+			if (defined $3) {
 				# Always strip leading/trailing parens then double quotes if existing
-				$title = substr($title, 1, -1);
+				$title = substr($3, 1, -1);
 				if ($title =~ /^".*"$/) {
 					$title = substr($title, 1, -1);
 					$title_has_quotes = 1;
 				}
+			} else {
+				$title = "commit title"
 			}
 
+
+			my $tag_case = not ($tag eq "Fixes:");
+			my $tag_space = not ($line =~ /^fixes:? [0-9a-f]{5,40} ($balanced_parens)/i);
+
+			my $id_length = not ($orig_commit =~ /^[0-9a-f]{12}$/i);
+			my $id_case = not ($orig_commit !~ /[A-F]/);
+
+			my $id = "0123456789ab";
 			my ($cid, $ctitle) = git_commit_info($orig_commit, $id,
 							     $title);