add POSIX clocks and timers maintainer

Update the MAINTAINERS file: Thomas Gleixner has been the de-facto
maintainer of POSIX timers and clocks for quite some time.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS

@@ -2857,8 +2857,8 @@ L:	linux-kernel@vger.kernel.org
 S:	Maintained
 
 POSIX CLOCKS and TIMERS
-P:	George Anzinger
-M:	george@mvista.com
+P:	Thomas Gleixner
+M:	tglx@linutronix.de
 L:	linux-kernel@vger.kernel.org
 S:	Supported