scripts/add_maintainers.pl: Remove hardcoding

Instead of using a hardcoded location, inherit the
location from $0

Signed-off-by: Lars Kurth <lars.kurth@citrix.com>
Acked-by: Julien Grall <julien.grall@arm.com>

scripts/add_maintainers.pl

@@ -26,9 +26,9 @@ sub insert ($$$$);
 sub hastag ($$);
 
 # Tool Variables
-my $get_maintainer      = "./scripts/get_maintainer.pl";
-
 my $tool = $0;
+my $get_maintainer = $tool;
+$get_maintainer =~ s/add_maintainers/get_maintainer/;
 my $usage = <<EOT;
 OPTIONS:
 --------