mm/gup: don't call __gup_longterm_locked() if FOLL_LONGTERM cannot be set

mm/gup: don't call __gup_longterm_locked() if FOLL_LONGTERM cannot be set

get_user_pages_remote(), get_user_pages_unlocked() and get_user_pages()
are never called with FOLL_LONGTERM, so directly call
__get_user_pages_locked()

The next patch will add an assertion for this.

Link: https://lkml.kernel.org/r/3-v2-987e91b59705+36b-gup_tidy_jgg@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Suggested-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>