MAINTAINERS: add pattern for dummy-tools

scripts/get_maintainer.pl does not find a maintainer for new files
otherwise.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

MAINTAINERS

@@ -9691,6 +9691,7 @@ F:	scripts/*vmlinux*
 F:	scripts/Kbuild*
 F:	scripts/Makefile*
 F:	scripts/basic/
+F:	scripts/dummy-tools/
 F:	scripts/mk*
 F:	scripts/mod/
 F:	scripts/package/