net: ena: handle bad request id in ena_netdev

After request id is checked in validate_rx_req_id() its value is still
used in the line
	rx_ring->free_ids[next_to_clean] =
					rx_ring->ena_bufs[i].req_id;
even if it was found to be out-of-bound for the array free_ids.

The patch moves the request id to an earlier stage in the napi routine and
makes sure its value isn't used if it's found out-of-bounds.

Fixes: 30623e1e ("net: ena: avoid memory access violation by validating req_id properly")
Signed-off-by: Ido Segev <idose@amazon.com>
Signed-off-by: Shay Agroskin <shayagr@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>