Remove check for None in RsaPrivate.make_key().

The variable rsa is never None if it is successfully created.
Under all other circumstances an exception is raised which will skip the
execution of the remainder of this method.

wolfcrypt/ciphers.py

@@ -829,8 +829,6 @@ if _lib.RSA_ENABLED:
                 Generates a new key pair of desired length **size**.
                 """
                 rsa = cls(hash_type=hash_type)
-                if rsa is None:  # pragma: no cover
-                    raise WolfCryptError("Invalid key error (%d)" % ret)
 
                 ret = _lib.wc_MakeRsaKey(rsa.native_object, size, 65537,
                         rng.native_object)