[IPV4]: Fix cut&paste error in fold_field.

net/ipv4/proc.c

@@ -99,7 +99,7 @@ fold_field(void *mib[], int nr)
 		    *((unsigned long *) (((void *) per_cpu_ptr(mib[0], i)) +
 					 sizeof (unsigned long) * nr));
 		res +=
-		    *((unsigned long *) (((void *) per_cpu_ptr(mib[0], i)) +
+		    *((unsigned long *) (((void *) per_cpu_ptr(mib[1], i)) +
 					 sizeof (unsigned long) * nr));
 	}
 	return res;