get_maintainer: use a default "unknown" S: status/role

When an "S:" status line is unavailable, use a default "unknown" role.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/get_maintainer.pl

@@ -931,7 +931,7 @@ sub get_maintainer_role {
     my $start = find_starting_index($index);
     my $end = find_ending_index($index);
 
-    my $role;
+    my $role = "unknown";
     my $subsystem = $typevalue[$start];
     if (length($subsystem) > 20) {
 	$subsystem = substr($subsystem, 0, 17);