arch/s390: teach arch_get_unmapped_area{_topdown} to handle hugetlb mappings

arch/s390: teach arch_get_unmapped_area{_topdown} to handle hugetlb mappings

We want to stop special casing hugetlb mappings and make them go through
generic channels, so teach arch_get_unmapped_area{_topdown} to handle
those.

s390 specific hugetlb function does not set info.align_offset, so do the
same here for compatibility.

Link: https://lkml.kernel.org/r/20241007075037.267650-3-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Donet Tom <donettom@linux.ibm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>