ixgbe: cleanup redundant default method set_rxpba

My original patch 6a14ee0cfb19 "ixgbe: Add X550 support function pointers"
accidental set a default value for this structure member twice.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c

@@ -1350,7 +1350,6 @@ static struct ixgbe_mac_operations mac_ops_X550 = {
 	.get_san_mac_addr	= &ixgbe_get_san_mac_addr_generic,
 	.get_wwn_prefix		= &ixgbe_get_wwn_prefix_generic,
 	.setup_link		= &ixgbe_setup_mac_link_X540,
-	.set_rxpba		= &ixgbe_set_rxpba_generic,
 	.get_link_capabilities	= &ixgbe_get_copper_link_capabilities_generic,
 	.setup_sfp		= NULL,
 };