ice: set tx_tstamps when creating new Tx rings via ethtool

When the user changes the number of queues via ethtool, the driver
allocates new rings. This allocation did not initialize tx_tstamps. This
results in the tx_tstamps field being zero (due to kcalloc allocation), and
would result in a NULL pointer dereference when attempting a transmit
timestamp on the new ring.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_ethtool.c

@@ -2826,6 +2826,7 @@ ice_set_ringparam(struct net_device *netdev, struct ethtool_ringparam *ring,
 		tx_rings[i].count = new_tx_cnt;
 		tx_rings[i].desc = NULL;
 		tx_rings[i].tx_buf = NULL;
+		tx_rings[i].tx_tstamps = &pf->ptp.port.tx;
 		err = ice_setup_tx_ring(&tx_rings[i]);
 		if (err) {
 			while (i--)