[PATCH] add MAINTAINERS entry for high-res timers, clockevents, dynticks

Thomas is the maintainer and primary author of the high-res timers,
clockevents and dynticks code.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>