Make log messages look slightly nicer.

I'd rather see the cipher and MAC named separately, with a hint that
the two are linked together in some way, than see the cipher called by
a name including the MAC and the MAC init message have an ugly
'<implicit>' in it.

sshccp.c

@@ -438,7 +438,7 @@ static const struct ssh_mac ssh2_poly1305 = {
     poly_start, poly_bytes, poly_genresult, poly_verresult,
 
     "", "", /* Not selectable individually, just part of ChaCha20-Poly1305 */
-    16, "<implicit>"
+    16, "Poly1305"
 };
 
 static void *ccp_make_context(void)
@@ -527,7 +527,7 @@ static const struct ssh2_cipher ssh2_chacha20_poly1305 = {
     ccp_decrypt_length,
 
     "chacha20-poly1305@openssh.com",
-    1, 512, SSH_CIPHER_SEPARATE_LENGTH, "ChaCha20 Poly1305",
+    1, 512, SSH_CIPHER_SEPARATE_LENGTH, "ChaCha20",
 
     &ssh2_poly1305
 };