net: atlantic: reduce scope of is_rsc_complete

Don't defer handling the err case outside the loop. That's pointless.

And since is_rsc_complete is only used inside this loop, declare
it inside the loop to reduce it's scope.

Signed-off-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>