mm: rmap.c: fix kernel-doc warning

After running make htmldocs, getting this warning
warning: Function parameter or member 'folio' not described in
'folio_move_anon_rmap'
and this patch resolves this warning

Link: https://lkml.kernel.org/r/20231006122825.54840-1-m.muzzammilashraf@gmail.com


Signed-off-by: Muhammad Muzammil <m.muzzammilashraf@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>