net: enetc: remove redundant clearing of skb/xdp_frame pointer in TX conf path

Later in enetc_clean_tx_ring we have:

		/* Scrub the swbd here so we don't have to do that
		 * when we reuse it during xmit
		 */
		memset(tx_swbd, 0, sizeof(*tx_swbd));

So these assignments are unnecessary.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>