selftests/resctrl: Add the test in MAINTAINERS

The resctrl selftest will be maintained by RDT maintainers.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

MAINTAINERS

@@ -14073,6 +14073,7 @@ S:	Supported
 F:	arch/x86/kernel/cpu/resctrl/
 F:	arch/x86/include/asm/resctrl_sched.h
 F:	Documentation/x86/resctrl*
+F:	tools/testing/selftests/resctrl/
 
 READ-COPY UPDATE (RCU)
 M:	"Paul E. McKenney" <paulmck@kernel.org>