i40e: Don't check for Tx hang when PF down

This patch adds check to bail out if device is already down when checking
for Tx hang subtask.

Change-ID: I3853fb7a6d11cb9a4c349b687cb25c15b19977a0
Signed-off-by: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -5587,7 +5587,8 @@ static void i40e_check_hang_subtask(struct i40e_pf *pf)
 	int i, v;
 
 	/* If we're down or resetting, just bail */
-	if (test_bit(__I40E_CONFIG_BUSY, &pf->state))
+	if (test_bit(__I40E_DOWN, &pf->state) ||
+	    test_bit(__I40E_CONFIG_BUSY, &pf->state))
 		return;
 
 	/* for each VSI/netdev