smb/client: properly disallow delegations on directories

smb/client: properly disallow delegations on directories

The check for S_ISREG() in cifs_setlease() is incorrect since that
operation doesn't get called for directories. The correct way to prevent
delegations on directories is to set the ->setlease() method in directory
file_operations to simple_nosetlease().

Fixes: e6d28ebc17eb ("filelock: push the S_ISREG check down to ->setlease handlers")
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260107-setlease-6-19-v1-2-85f034abcc57@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>