MAINTAINERS: add missing percpu-internal.h file to per-cpu section

This file seems to most appropriately belong to the PER-CPU MEMORY
ALLOCATOR section, so place it there.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Lorenzo Stoakes <[email protected]>
Cc: Alistair Popple <[email protected]>
Cc: Christoph Lameter (Ampere) <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Liam Howlett <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Nico Pache <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Qi Zheng <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: Dev Jain <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Pedro Falcato <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Joshua Hahn <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: lorenzo-stoakes

MAINTAINERS

@@ -19459,6 +19459,7 @@ F:	arch/*/include/asm/percpu.h
 F:	include/linux/percpu*.h
 F:	lib/percpu*.c
 F:	mm/percpu*.c
+F:	mm/percpu-internal.h
 
 PER-TASK DELAY ACCOUNTING
 M:	Balbir Singh <[email protected]>