DCB: Add interface to query the state of PFC feature.

Adds a netlink interface for Data Center Bridging (DCB) to get and set
the enable state of the Priority Flow Control (PFC) feature.
Primarily, this is a way to turn off PFC in the driver while DCB
remains enabled.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/dcbnl.h b/include/net/dcbnl.h
index f0a6528..c7d87ca 100644
--- a/include/net/dcbnl.h
+++ b/include/net/dcbnl.h
@@ -42,6 +42,8 @@
 	u8   (*getcap)(struct net_device *, int, u8 *);
 	u8   (*getnumtcs)(struct net_device *, int, u8 *);
 	u8   (*setnumtcs)(struct net_device *, int, u8);
+	u8   (*getpfcstate)(struct net_device *);
+	void (*setpfcstate)(struct net_device *, u8);
 };
 
 #endif /* __NET_DCBNL_H__ */