vboxsf: explicitly deny setlease attempts

vboxsf does not break leases on its own, so it can't properly handle the
case where the hypervisor changes the data. Don't allow file leases on
vboxsf.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20240319-setlease-v1-1-5997d67e04b3@kernel.org
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>