MAINTAINERS: add myself as arm perf reviewer

As suggested by Will Deacon, add myself as a reviewer of the ARM PMU
profiling and debugging code.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

MAINTAINERS

@@ -822,6 +822,7 @@ F:	arch/arm/include/asm/floppy.h
 
 ARM PMU PROFILING AND DEBUGGING
 M:	Will Deacon <will.deacon@arm.com>
+R:	Mark Rutland <mark.rutland@arm.com>
 S:	Maintained
 F:	arch/arm*/kernel/perf_*
 F:	arch/arm/oprofile/common.c