mm/madvise: remove len parameter of madvise_do_behavior()

Because madise_should_skip() logic is factored out, making
madvise_do_behavior() calculates 'len' on its own rather then receiving it
as a parameter makes code simpler.  Remove the parameter.

Link: https://lkml.kernel.org/r/20250312164750.59215-5-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liam R. Howlett <howlett@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>