arch/x86: teach arch_get_unmapped_area_vmflags to handle hugetlb mappings

arch/x86: teach arch_get_unmapped_area_vmflags 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_}vmflags to
handle those.

x86 specific hugetlb function does not set either info.start_gap or
info.align_offset so the same here for compatibility.

Link: https://lkml.kernel.org/r/20241007075037.267650-4-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>