cifs: remove useless memset in LANMAN auth code

It turns out that CIFS_SESS_KEY_SIZE == CIFS_ENCPWD_SIZE, so this
memset doesn't do anything useful.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifsencrypt.c

@@ -276,7 +276,6 @@ int calc_lanman_hash(const char *password, const char *cryptkey, bool encrypt,
 		strncpy(password_with_pad, password, CIFS_ENCPWD_SIZE);
 
 	if (!encrypt && global_secflags & CIFSSEC_MAY_PLNTXT) {
-		memset(lnm_session_key, 0, CIFS_SESS_KEY_SIZE);
 		memcpy(lnm_session_key, password_with_pad,
 			CIFS_ENCPWD_SIZE);
 		return 0;