ndis(4): Undo unneeded workarounds in ndis' rand().

- Revert the change for seed(0) in r300384. I misunderstood the standard
and while our random() implementation in libkern may be improved, it
handles the seed(0) case fine.

Pointed out by:	bde, ache

sys/compat/ndis/subr_ntoskrnl.c

@@ -3196,8 +3196,6 @@ static void
 srand(unsigned int seed)
 {
 
-	if (seed == 0)
-		seed = 1;
 	srandom(seed);
 }