MAINTAINERS: Make Dennis the percpu tree maintainer

Dennis rewrote a significant portion of the percpu allocator and has
shown that he can respond in a timely and helpful manner when issues
are reported against percpu allocator.

Let's make Dennis the percpu tree maintainer.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Christoph Lameter <cl@linux.com>

MAINTAINERS

@@ -11360,10 +11360,10 @@ S:	Maintained
 F:	drivers/platform/x86/peaq-wmi.c
 
 PER-CPU MEMORY ALLOCATOR
+M:	Dennis Zhou <dennis@kernel.org>
 M:	Tejun Heo <tj@kernel.org>
 M:	Christoph Lameter <cl@linux.com>
-M:	Dennis Zhou <dennisszhou@gmail.com>
-T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu.git
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu.git
 S:	Maintained
 F:	include/linux/percpu*.h
 F:	mm/percpu*.c