Remove dead code in pack_public_key_ed25519

if (ret != 0)
		free(response->public_key);

is dead code; the very last operation before the memcpy and the setting of ret to 0 is the malloc of response->public_key, which means response->public_key is always NULL if pack_public_key_ed25519 fails.

sk-usbhid.c

@@ -696,8 +696,6 @@ pack_public_key_ed25519(const fido_cred_t *cred,
 	memcpy(response->public_key, ptr, len);
 	ret = 0;
  out:
-	if (ret != 0)
-		free(response->public_key);
 	return ret;
 }