ixgbevf - Remove unused parameter in ixgbevf_receive_skb

Remove 'rx_ring' parameter as it is not used in ixgbevf_receive_skb

Signed-off-by: Narendra K <narendra_k@dell.com>
Acked-by: Greg Rose <gregory.v.rose@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>