fix syntax

pallets/duniter-account/src/lib.rs

@@ -336,8 +336,7 @@ where
     T: Config,
 {
     fn link_identity(account_id: T::AccountId, idty_id: IdtyIdOf<T>) -> Result<(), DispatchError> {
-        Self::do_link_identity(account_id, idty_id)?;
-        Ok(())
+        Self::do_link_identity(account_id, idty_id)
     }
 }