Remove bogus error message from qemu_opts_set()

The only way qemu_opts_create() can fail is if a QemuOpts with that id
already exists and fail_if_exists=1. In that case, we already print
an error which makes more sense than the one in qemu_opts_set().

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

qemu-option.c

@@ -670,8 +670,6 @@ int qemu_opts_set(QemuOptsList *list, const char *id,
 
     opts = qemu_opts_create(list, id, 1);
     if (opts == NULL) {
-        fprintf(stderr, "id \"%s\" not found for \"%s\"\n",
-                id, list->name);
         return -1;
     }
     return qemu_opt_set(opts, name, value);