MAINTAINERS: remove unused TIMEKEEPING timekeeping.h

Commit 88606e8 ("MAINTAINERS: Update timer related entries") added a
file pattern that didn't actually exist.

Signed-off-by: Joe Perches <joe@perches.com>
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

@@ -5420,7 +5420,6 @@ S:	Supported
 F:	include/linux/clocksource.h
 F:	include/linux/time.h
 F:	include/linux/timex.h
-F:	include/linux/timekeeping.h
 F:	kernel/time/clocksource.c
 F:	kernel/time/time*.c
 F:	kernel/time/ntp.c