crypto/rsakey-builtin.c.inc: Clean up two error paths

When qcrypto_builtin_rsa_public_key_parse() is about to fail, but no
error has been set, it makes one up.  Actually, there's just one way
to fail without setting an error.  Set it there instead.

Same for qcrypto_builtin_rsa_private_key_parse().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

crypto/rsakey-builtin.c.inc

@@ -88,15 +88,13 @@ static QCryptoAkCipherRSAKey *qcrypto_builtin_rsa_public_key_parse(
         goto error;
     }
     if (seq_length != 0) {
+        error_setg(errp, "Invalid RSA public key");
         goto error;
     }
 
     return rsa;
 
 error:
-    if (errp && !*errp) {
-        error_setg(errp, "Invalid RSA public key");
-    }
     qcrypto_akcipher_rsakey_free(rsa);
     return NULL;
 }
@@ -169,15 +167,13 @@ static QCryptoAkCipherRSAKey *qcrypto_builtin_rsa_private_key_parse(
         return rsa;
     }
     if (seq_length != 0) {
+        error_setg(errp, "Invalid RSA private key");
         goto error;
     }
 
     return rsa;
 
 error:
-    if (errp && !*errp) {
-        error_setg(errp, "Invalid RSA private key");
-    }
     qcrypto_akcipher_rsakey_free(rsa);
     return NULL;
 }