[PATCH RESEND] checkpatch: Fix NOT_UNIFIED_DIFF error exception

["Matthew R. Ochs" <mrochs@linux.vnet.ibm.com>]

Commit 06330fc40e3f ("checkpatch: Avoid NOT_UNIFIED_DIFF
errors on cover-letter.patch files") added an exception to bypass
the unified-diff check for cover letters. The patch evaluates the
cover letter regex against $file. Instead it should use $filename.

This patch corrects the variable.

Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
---
I originally sent this out in late September but it appears to
have been missed. As a fix to avoid a false positive warning I'd
like to see it make it to 'next'.

 scripts/checkpatch.pl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index f2a1131..fdb1e48 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5808,7 +5808,7 @@ sub process {
 		exit(0);
 	}
 
-	if (!$is_patch && $file !~ /cover-letter\.patch$/) {
+	if (!$is_patch && $filename !~ /cover-letter\.patch$/) {
 		ERROR("NOT_UNIFIED_DIFF",
 		      "Does not appear to be a unified-diff format patch\n");
 	}
-- 
2.1.0