net: aquantia: Add tx clean budget and valid budget handling logic

We should report to napi full budget only when we have more job to do.
Before this fix, on any tx queue cleanup we forced napi to do poll again.
Thats a waste of cpu resources and caused storming with napi polls when
there was at least one tx on each interrupt.

With this fix we report full budget only when there is more job on TX
to do. Or, as before, when rx budget was fully consumed.

Signed-off-by: Igor Russkikh <igor.russkikh@aquantia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>