MAINTAINERS: remove arch/*/lib/perf_event*.c

This pattern only matched arch/frv/lib/perf_event.c, which was removed
by commit e360adbe ("irq_work: Add generic hardirq context
callbacks").

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>