ice: set tx_tstamps when creating new Tx rings via ethtool

In the Linux kernel, the following vulnerability has been resolved:

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.