ixgbe: Enable another bit for flow control operation

The discard pause frames bit was not enabled, so flow control frames could
be passed up to the host.  Enabled DPF to keep the frames off the stack.

Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@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_common.c b/drivers/net/ixgbe/ixgbe_common.c
index 63ab667..846c9de 100644
--- a/drivers/net/ixgbe/ixgbe_common.c
+++ b/drivers/net/ixgbe/ixgbe_common.c
@@ -1700,6 +1700,7 @@
 	}
 
 	/* Enable 802.3x based flow control settings. */
+	mflcn_reg |= IXGBE_MFLCN_DPF;
 	IXGBE_WRITE_REG(hw, IXGBE_MFLCN, mflcn_reg);
 	IXGBE_WRITE_REG(hw, IXGBE_FCCFG, fccfg_reg);