Fix the error on overly large group orders.

Change-Id: I9b11fabb79b5dfe031ac5ea2f021b28b87262761
Reviewed-on: https://boringssl-review.googlesource.com/27585
Reviewed-by: Adam Langley <alangley@gmail.com>

crypto/fipsmodule/ec/ec.c

@@ -352,7 +352,7 @@ int EC_GROUP_set_generator(EC_GROUP *group, const EC_POINT *generator,
   }
 
   if (BN_num_bytes(order) > EC_MAX_SCALAR_BYTES) {
-    OPENSSL_PUT_ERROR(EC, EC_R_INVALID_FIELD);
+    OPENSSL_PUT_ERROR(EC, EC_R_INVALID_GROUP_ORDER);
     return 0;
   }