MAINTAINERS: Change maintainer for RDT

Due to job transition, I am stepping down as RDT maintainer.
Add Tony as a co-maintainer.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Reinette Chatre <reinette.chatre@intel.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/all/20250131190731.3981085-1-fenghua.yu%40intel.com