mm: kill mm_wr_locked from unmap_vmas() and unmap_single_vma()

mm: kill mm_wr_locked from unmap_vmas() and unmap_single_vma()

Kill mm_wr_locked since commit f8e97613fed2 ("mm: convert VM_PFNMAP
tracking to pfnmap_track() + pfnmap_untrack()") remove the user.

Link: https://lkml.kernel.org/r/20251104085709.2688433-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>