i40e/i40evf: remove mismatched type warnings

Compiler reported several places where driver compared
signed and unsigned types.  Cast or change the types to remove
the warnings.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 22e6084..a2d6651 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -4773,7 +4773,7 @@ static void i40e_detect_recover_hung(struct i40e_pf *pf)
 {
 	struct net_device *netdev;
 	struct i40e_vsi *vsi;
-	int i;
+	unsigned int i;
 
 	/* Only for LAN VSI */
 	vsi = pf->vsi[pf->lan_vsi];