MAINTAINERS: Update the MODULE SUPPORT section

Change my role for MODULE SUPPORT from a reviewer to a maintainer. We
started to rotate its maintainership and I currently look after the modules
tree. This not being reflected in MAINTAINERS proved to confuse folks.

Add lib/tests/module/ and tools/testing/selftests/module/ to maintained
files. They were introduced previously by commit 84b4a51f ("selftests:
add new kallsyms selftests").

Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20250306162117.18876-1-petr.pavlu@suse.com


Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>