headers/deps: mm: align MANITAINERS and Docs with new gfp.h structure

After moving gfp types out of gfp.h, we have to align MAINTAINERS
and Docs, to avoid warnings like this:

>> include/linux/gfp.h:1: warning: 'Page mobility and placement hints' not found
>> include/linux/gfp.h:1: warning: 'Watermark modifiers' not found
>> include/linux/gfp.h:1: warning: 'Reclaim modifiers' not found
>> include/linux/gfp.h:1: warning: 'Useful GFP flag combinations' not found
Signed-off-by: Yury Norov <yury.norov@gmail.com>

Documentation/core-api/mm-api.rst

@@ -22,16 +22,16 @@ Memory Allocation Controls
 .. kernel-doc:: include/linux/gfp.h
    :internal:
 
-.. kernel-doc:: include/linux/gfp.h
+.. kernel-doc:: include/linux/gfp_types.h
    :doc: Page mobility and placement hints
 
-.. kernel-doc:: include/linux/gfp.h
+.. kernel-doc:: include/linux/gfp_types.h
    :doc: Watermark modifiers
 
-.. kernel-doc:: include/linux/gfp.h
+.. kernel-doc:: include/linux/gfp_types.h
    :doc: Reclaim modifiers
 
-.. kernel-doc:: include/linux/gfp.h
+.. kernel-doc:: include/linux/gfp_types.h
    :doc: Useful GFP flag combinations
 
 The Slab Cache

MAINTAINERS

@@ -12850,6 +12850,7 @@ T:	quilt https://ozlabs.org/~akpm/mmotm/
 T:	quilt https://ozlabs.org/~akpm/mmots/
 T:	git git://github.com/hnaz/linux-mm.git
 F:	include/linux/gfp.h
+F:	include/linux/gfp_types.h
 F:	include/linux/memory_hotplug.h
 F:	include/linux/mm.h
 F:	include/linux/mmzone.h