ppp_generic: fix multilink fragment sizes

Fix bug in multilink fragment size calculation introduced by
commit 9c705260
"ppp: ppp_mp_explode() redesign"
Signed-off-by: NBen McKeegan <ben@netservers.co.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ppp_generic.c

@@ -1422,7 +1422,7 @@ static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
 		flen = len;
 		if (nfree > 0) {
 			if (pch->speed == 0) {
-				flen = totlen/nfree;
+				flen = len/nfree;
 				if (nbigger > 0) {
 					flen++;
 					nbigger--;