ixgbe: only check pfc bits in hang logic if pfc is enabled

Only check pfc bits in hang logic if PFC is enabled.  Previously,
if DCB was enabled but PFC was disabled the incorrect pause
bits would be checked.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Don Skidmore <donald.c.skidmore@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ixgbe/ixgbe_main.c b/drivers/net/ixgbe/ixgbe_main.c
index d571d10..b2af2f6 100644
--- a/drivers/net/ixgbe/ixgbe_main.c
+++ b/drivers/net/ixgbe/ixgbe_main.c
@@ -642,7 +642,7 @@
 	u32 txoff = IXGBE_TFCS_TXOFF;
 
 #ifdef CONFIG_IXGBE_DCB
-	if (adapter->flags & IXGBE_FLAG_DCB_ENABLED) {
+	if (adapter->dcb_cfg.pfc_mode_enable) {
 		int tc;
 		int reg_idx = tx_ring->reg_idx;
 		int dcb_i = adapter->ring_feature[RING_F_DCB].indices;