Fix regression in i2d_re_X509_REQ_tbs()

This fixes regression from commit 8e39049. There is also no point
in setting the modified flag after just calling i2d.

Fixes #19297

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: David von Oheimb <david.von.oheimb@siemens.com>
(Merged from #19299)

crypto/x509/x509_req.c

@@ -309,8 +309,6 @@ int i2d_re_X509_REQ_tbs(X509_REQ *req, unsigned char **pp)
         ERR_raise(ERR_LIB_X509, ERR_R_PASSED_NULL_PARAMETER);
         return 0;
     }
-    if (!i2d_X509_REQ_INFO(&req->req_info, pp))
-        return 0;
     req->req_info.enc.modified = 1;
-    return 1;
+    return i2d_X509_REQ_INFO(&req->req_info, pp);
 }