i40e: fix PTP bug

The receive hang detection routine was never being run when
PTP was enabled.

Change-ID: I200f35b0f3190d31b595df89d678f4c8a2131ba0
Signed-off-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: NJim Young <jamesx.m.young@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_ptp.c

@@ -247,7 +247,7 @@ void i40e_ptp_rx_hang(struct i40e_vsi *vsi)
 	u32 prttsyn_stat;
 	int n;
 
-	if (pf->flags & I40E_FLAG_PTP)
+	if (!(pf->flags & I40E_FLAG_PTP))
 		return;
 
 	prttsyn_stat = rd32(hw, I40E_PRTTSYN_STAT_1);