cifs: Fix missed free operations

cifs_setattr_nounix has two paths which miss free operations
for xid and fullpath.
Use goto cifs_setattr_exit like other paths to fix them.

CC: Stable <stable@vger.kernel.org>
Fixes: aa081859 ("cifs: flush before set-info if we have writeable handles")
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>