i40e: Fix unexpected MFS warning message

Commit 3a2c6ced ("i40e: Add a check to see if MFS is set") added
a warning message that reports unexpected size of port's MFS (max
frame size) value. This message use for the port number local
variable 'i' that is wrong.
In i40e_probe() this 'i' variable is used only to iterate VSIs
to find FDIR VSI:

<code>
...
/* if FDIR VSI was set up, start it now */
        for (i = 0; i < pf->num_alloc_vsi; i++) {
                if (pf->vsi[i] && pf->vsi[i]->type == I40E_VSI_FDIR) {
                        i40e_vsi_open(pf->vsi[i]);
                        break;
                }
        }
...
</code>

So the warning message use for the port number index of FDIR VSI
if this exists or pf->num_alloc_vsi if not.

Fix the message by using 'pf->hw.port' for the port number.

Fixes: 3a2c6ced ("i40e: Add a check to see if MFS is set")
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -16224,7 +16224,7 @@ static int i40e_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	       I40E_PRTGL_SAH_MFS_MASK) >> I40E_PRTGL_SAH_MFS_SHIFT;
 	if (val < MAX_FRAME_SIZE_DEFAULT)
 		dev_warn(&pdev->dev, "MFS for port %x has been set below the default: %x\n",
-			 i, val);
+			 pf->hw.port, val);
 
 	/* Add a filter to drop all Flow control frames from any VSI from being
 	 * transmitted. By doing so we stop a malicious VF from sending out