mm/gup_test: fix ioctl fail for compat task

When tools/testing/selftests/mm/gup_test.c is compiled as 32bit, then run
on arm64 kernel, it reports "ioctl: Inappropriate ioctl for device".

Fix it by filling compat_ioctl in gup_test_fops

Link: https://lkml.kernel.org/r/20230526022125.175728-1-haibo.li@mediatek.com
Signed-off-by: Haibo Li <haibo.li@mediatek.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/gup_test.c

diff --git a/mm/gup_test.c b/mm/gup_test.c
index 8ae7307..c0421b7 100644
--- a/mm/gup_test.c
+++ b/mm/gup_test.c
@@ -381,6 +381,7 @@ static int gup_test_release(struct inode *inode, struct file *file)
 static const struct file_operations gup_test_fops = {
 	.open = nonseekable_open,
 	.unlocked_ioctl = gup_test_ioctl,
+	.compat_ioctl = compat_ptr_ioctl,
 	.release = gup_test_release,
 };