i40e: get rid of magic number

BugLink: http://bugs.launchpad.net/bugs/1547674

We have a define for this, use it. No functional change.

Change-ID: Ic0e3ea4f562e46de63b2a8de07f291ccc10205fd
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
(cherry picked from net-next commit d6b3bca1)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c

@@ -461,7 +461,7 @@ static int i40e_config_vsi_rx_queue(struct i40e_vf *vf, u16 vsi_id,
 		rx_ctx.hbuff = info->hdr_size >> I40E_RXQ_CTX_HBUFF_SHIFT;
 
 		/* set splitalways mode 10b */
-		rx_ctx.dtype = 0x2;
+		rx_ctx.dtype = I40E_RX_DTYPE_HEADER_SPLIT;
 	}
 
 	/* databuffer length validation */