ppp: Remove redundant BUG_ON() check in ppp_pernet

Passing NULL to ppp_pernet causes a crash via BUG_ON.
Dereferencing net in net_generic() also has the same effect.
This patch removes the redundant BUG_ON check on the same parameter.

Signed-off-by: Xu Wang <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ppp/ppp_generic.c

···
 /* per net-namespace data */
 static inline struct ppp_net *ppp_pernet(struct net *net)
 {
-	BUG_ON(!net);
-
 	return net_generic(net, ppp_net_id);
 }