docs(maintainers): add code owners for runtime services module

This patch adds code owners responsible for maintaining source files
related to runtime services functionality in TF-A.

Change-Id: I24fbbfd017f90a4fae2ffbb94c8eb81d0d837f8e
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
1 file changed