cifs: free nativeFileSystem field before allocating a new one

...otherwise, we'll leak this memory if we have to reconnect (e.g. after
network failure).

Signed-off-by: Jeff Layton <jlayton@redhat.com>
CC: Stable <stable@kernel.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>
1 file changed