hfsplus: write up fsync for directories

fsync is supposed to not just work on regular files, but also on
directories.  Fortunately enough hfsplus_file_fsync works just fine
for directories, so we can just wire it up.

Signed-off-by: Christoph Hellwig <hch@tuxera.com>
diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c
index 9d59c05..e44c78a 100644
--- a/fs/hfsplus/dir.c
+++ b/fs/hfsplus/dir.c
@@ -485,6 +485,7 @@
 };
 
 const struct file_operations hfsplus_dir_operations = {
+	.fsync		= hfsplus_file_fsync,
 	.read		= generic_read_dir,
 	.readdir	= hfsplus_readdir,
 	.unlocked_ioctl = hfsplus_ioctl,