gfs2: don't allow delegations to be set on directories

With the advent of directory leases, it's necessary to set the
->setlease() handler in directory file_operations to properly deny them.

In the "nolock" case however, there is no need to deny them.

Fixes: e6d28ebc17eb ("filelock: push the S_ISREG check down to ->setlease handlers")
Signed-off-by: Jeff Layton <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Christian Brauner <[e-mail]>

fs/gfs2/file.c

···
 	.lock		= gfs2_lock,
 	.flock		= gfs2_flock,
 	.llseek		= default_llseek,
+	.setlease	= simple_nosetlease,
 	.fop_flags	= FOP_ASYNC_LOCK,
 };