net/ionic: avoid OOB TX partner lookup for hwstamp RXQ

In the Linux kernel, the following vulnerability has been resolved: net/ionic: avoid OOB TX partner lookup for hwstamp RXQ The dedicated hardware timestamp RX queue is allocated with q->index equal to lif->ionic->nrxqs_per_lif. The normal txqcqs array only contains the regular queue pairs, so using that index to set rxq->partner can read one entry past txqcqs[] and then write through the derived pointer. Only link RX/TX partners for normal queue-pair indexes. Leave the hwstamp RX queue unpaired, and make the XDP_TX path abort cleanly if an RX queue has no TX partner.