net: ena: Fix bug where ring allocation backoff stopped too late

The current code of create_queues_with_size_backoff() allows the ring size
to become as small as ENA_MIN_RING_SIZE/2. This is a bug since we don't
want the queue ring to be smaller than ENA_MIN_RING_SIZE

In this commit we change the loop's termination condition to look at the
queue size of the next iteration instead of that of the current one,
so that the minimal queue size again becomes ENA_MIN_RING_SIZE.

Fixes: eece4d2a ("net: ena: add ethtool function for changing io queue sizes")

Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: Sameeh Jubran <sameehj@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>