fou: Add GRO support

Implement fou_gro_receive and fou_gro_complete, and populate these
in the correponsing udp_offloads for the socket. Added ipproto to
udp_offloads and pass this from UDP to the fou GRO routine in proto
field of napi_gro_cb structure.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 28d4378..4354b43 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1874,7 +1874,7 @@
 	/* jiffies when first packet was created/queued */
 	unsigned long age;
 
-	/* Used in ipv6_gro_receive() */
+	/* Used in ipv6_gro_receive() and foo-over-udp */
 	u16	proto;
 
 	/* Used in udp_gro_receive */
@@ -1925,6 +1925,7 @@
 
 struct udp_offload {
 	__be16			 port;
+	u8			 ipproto;
 	struct offload_callbacks callbacks;
 };