ksmbd: call putname after using the last component

last component point filename struct. Currently putname is called after
vfs_path_parent_lookup(). And then last component is used for
lookup_one_qstr_excl(). name in last component is freed by previous
calling putname(). And It cause file lookup failure when testing
generic/464 test of xfstest.

Fixes: 74d7970f

 ("ksmbd: fix racy issue from using ->d_parent and ->d_name")
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>