scripts: fix error from checkpatch.pl when no commits are found

The error message was supposed to mention the input revision list start
point, not the branch flag.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20201019143537.283094-3-berrange@redhat.com>
Message-Id: <20201021163136.27324-6-alex.bennee@linaro.org>
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 6ed3497..88c858f 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -392,7 +392,7 @@
 
 	close $HASH;
 
-	die "$P: no revisions returned for revlist '$chk_branch'\n"
+	die "$P: no revisions returned for revlist '$ARGV[0]'\n"
 	    unless @patches;
 
 	my $i = 1;