ceph: delete an unnecessary return statement in update_dentry_lease()

The script "checkpatch.pl" pointed information out like the following.

WARNING: void function return statements are not generally useful

Thus remove such a statement in the affected function.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Yan, Zheng <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>