MAINTAINERS: add memory mapping/VMA co-maintainers

Add myself and Liam as co-maintainers of the memory mapping and VMA code
alongside Andrew as we are heavily involved in its implementation and
maintenance.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Lorenzo Stoakes <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Liam R. Howlett <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

MAINTAINERS

@@ -14907,9 +14907,9 @@ N:	include/linux/page[-_]*
 
 MEMORY MAPPING
 M:	Andrew Morton <[email protected]>
-R:	Liam R. Howlett <[email protected]>
+M:	Liam R. Howlett <[email protected]>
+M:	Lorenzo Stoakes <[email protected]>
 R:	Vlastimil Babka <[email protected]>
-R:	Lorenzo Stoakes <[email protected]>
 L:	[email protected]
 S:	Maintained
 W:	http://www.linux-mm.org
@@ -24737,9 +24737,9 @@ F:	tools/testing/vsock/
 
 VMA
 M:	Andrew Morton <[email protected]>
-R:	Liam R. Howlett <[email protected]>
+M:	Liam R. Howlett <[email protected]>
+M:	Lorenzo Stoakes <[email protected]>
 R:	Vlastimil Babka <[email protected]>
-R:	Lorenzo Stoakes <[email protected]>
 L:	[email protected]
 S:	Maintained
 W:	https://www.linux-mm.org