net: mvpp2: remove unused 'tx_skb' field of 'struct mvpp2_tx_queue'

This commit remove a field of 'struct mvpp2_tx_queue' that is not used
anywhere.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mvpp2.c

@@ -823,9 +823,6 @@ struct mvpp2_tx_queue {
 	/* Per-CPU control of physical Tx queues */
 	struct mvpp2_txq_pcpu __percpu *pcpu;
 
-	/* Array of transmitted skb */
-	struct sk_buff **tx_skb;
-
 	u32 done_pkts_coal;
 
 	/* Virtual address of thex Tx DMA descriptors array */