pppoe: remove redundant BUG_ON() check in pppoe_pernet

Passing NULL to pppoe_pernet causes a crash via BUG_ON.
Dereferencing net in net_generici() also has the same effect. This patch
removes the redundant BUG_ON check on the same parameter.
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ppp/pppoe.c

@@ -119,8 +119,6 @@ static inline bool stage_session(__be16 sid)
 
 static inline struct pppoe_net *pppoe_pernet(struct net *net)
 {
-	BUG_ON(!net);
-
 	return net_generic(net, pppoe_net_id);
 }