scripts/checkpatch: Do not use mailmap

The .mailmap file fixes mistake we already did.
Do not use it when running checkpatch.pl, otherwise
we might commit the very same mistakes.

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

scripts/checkpatch.pl

@@ -435,8 +435,8 @@ if ($chk_branch) {
 	my @patches;
 	my %git_commits = ();
 	my $HASH;
-	open($HASH, "-|", "git", "log", "--reverse", "--no-merges", "--format=%H %s", $ARGV[0]) ||
-		die "$P: git log --reverse --no-merges --format='%H %s' $ARGV[0] failed - $!\n";
+	open($HASH, "-|", "git", "log", "--reverse", "--no-merges", "--no-mailmap", "--format=%H %s", $ARGV[0]) ||
+		die "$P: git log --reverse --no-merges --no-mailmap --format='%H %s' $ARGV[0] failed - $!\n";
 
 	for my $line (<$HASH>) {
 		$line =~ /^([0-9a-fA-F]{40,40}) (.*)$/;
@@ -460,7 +460,7 @@ if ($chk_branch) {
                      "-c", "diff.renamelimit=0",
                      "-c", "diff.renames=True",
                      "-c", "diff.algorithm=histogram",
-                     "show",
+                     "show", "--no-mailmap",
                      "--patch-with-stat", $hash) ||
 			die "$P: git show $hash - $!\n";
 		while (<$FILE>) {