net: phy: bcm7xxx: Add entry for BCM7278

Add support for the BCM7278 28nm process Gigabit Ethernet PHY.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/brcmphy.h b/include/linux/brcmphy.h
index 4f7d8be..295fb3e 100644
--- a/include/linux/brcmphy.h
+++ b/include/linux/brcmphy.h
@@ -24,6 +24,7 @@
 #define PHY_ID_BCM57780			0x03625d90
 
 #define PHY_ID_BCM7250			0xae025280
+#define PHY_ID_BCM7278			0xae0251a0
 #define PHY_ID_BCM7364			0xae025260
 #define PHY_ID_BCM7366			0x600d8490
 #define PHY_ID_BCM7346			0x600d8650