mm/munlock: remove fields to fix htmldocs warnings

mm/munlock: remove fields to fix htmldocs warnings

Stephen reports that 'make htmldocs' currently issues two warnings:

include/linux/mm_types.h:275: warning: Function parameter or member
'__filler' not described in 'folio'
include/linux/mm_types.h:275: warning: Function parameter or member
'mlock_count' not described in 'folio'

Certainly __filler doesn't want documenting there, and all but one use of
mlock_count is through page->mlock_count at present: so I think it's best
just to remove them both from struct folio for now, and sort out the right
way to document folio->mlock_count once that is the one true way.

Link: https://lkml.kernel.org/r/d2c8f66d-be8e-7c91-b0c8-b2f7ffb08bec@google.com
Fixes: 07ca76067308 ("mm/munlock: maintain page->mlock_count while unevictable")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>