eth: igc: remove unused embedded struct net_device

struct net_device poll_dev in struct igc_q_vector was added
in one of the initial commits, but never used.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/igc/igc.h

@@ -570,7 +570,6 @@ struct igc_q_vector {
 
 	struct rcu_head rcu;    /* to avoid race with update stats on free */
 	char name[IFNAMSIZ + 9];
-	struct net_device poll_dev;
 
 	/* for dynamic allocation of rings associated with this q_vector */
 	struct igc_ring ring[] ____cacheline_internodealigned_in_smp;