nilfs2: add compat ioctl

The current FS_IOC_GETFLAGS/SETFLAGS/GETVERSION will fail if
application is 32 bit and kernel is 64 bit.

This issue is avoidable by adding compat_ioctl method.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/dir.c b/fs/nilfs2/dir.c
index b72833a..3a19239 100644
--- a/fs/nilfs2/dir.c
+++ b/fs/nilfs2/dir.c
@@ -681,7 +681,7 @@
 	.readdir	= nilfs_readdir,
 	.unlocked_ioctl	= nilfs_ioctl,
 #ifdef CONFIG_COMPAT
-	.compat_ioctl	= nilfs_ioctl,
+	.compat_ioctl	= nilfs_compat_ioctl,
 #endif	/* CONFIG_COMPAT */
 	.fsync		= nilfs_sync_file,