MAINTAINERS: update page allocator section

Make Vlastimil maintainer of this section (with thanks to Vlastimil for
agreeing to this!) and add page isolation files for which this section
seem most appropriate.

We may wish to, in future, refactor/rename some of these files to more
logically fit what is actually being performed, but for the time being
this seems the most sensible place.

Additionally, fix the alphabetical ordering of files.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Lorenzo Stoakes <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Acked-by: Zi Yan <[email protected]>
Cc: Brendan Jackman <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: lorenzo-stoakes

MAINTAINERS

@@ -15566,18 +15566,20 @@ F:	mm/numa_memblks.c
 
 MEMORY MANAGEMENT - PAGE ALLOCATOR
 M:	Andrew Morton <[email protected]>
-R:	Vlastimil Babka <[email protected]>
+M:	Vlastimil Babka <[email protected]>
 R:	Suren Baghdasaryan <[email protected]>
 R:	Michal Hocko <[email protected]>
 R:	Brendan Jackman <[email protected]>
 R:	Johannes Weiner <[email protected]>
 R:	Zi Yan <[email protected]>
 L:	[email protected]
 S:	Maintained
+F:	include/linux/compaction.h
+F:	include/linux/gfp.h
+F:	include/linux/page-isolation.h
 F:	mm/compaction.c
 F:	mm/page_alloc.c
-F:	include/linux/gfp.h
-F:	include/linux/compaction.h
+F:	mm/page_isolation.c
 
 MEMORY MANAGEMENT - RMAP (REVERSE MAPPING)
 M:	Andrew Morton <[email protected]>