ixgbe: Drop unnecessary addition from ixgbe_set_rx_buffer_len

We still had some code floating around from the old single buffer receive
path.  As a result we were adding VLAN_HLEN to max_frame although the
resultant value was never used.  Since that is the case we can drop this from
the function.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -3289,9 +3289,6 @@ static void ixgbe_set_rx_buffer_len(struct ixgbe_adapter *adapter)
 		IXGBE_WRITE_REG(hw, IXGBE_MHADD, mhadd);
 	}
 
-	/* MHADD will allow an extra 4 bytes past for vlan tagged frames */
-	max_frame += VLAN_HLEN;
-
 	hlreg0 = IXGBE_READ_REG(hw, IXGBE_HLREG0);
 	/* set jumbo enable since MHADD.MFS is keeping size locked at max_frame */
 	hlreg0 |= IXGBE_HLREG0_JUMBOEN;