drivers/net/slip.c: Fix another compilation error

ChangeLog

@@ -10776,7 +10776,7 @@
 	  Based comments from Anton D. Kachalov (2015-07-29).
 	* STM32 F4:  Add DMA support to the ADC driver for STM32 F4.  From
 	  Max Kriegler (2015-07-30).
-	* sem_tickwait():  Added this furnction for internaluse within the
+	* sem_tickwait():  Added this function for internal use within the
 	  OS.  It is a non-standard but more efficient version of sem_timedwait()
-	  for use in higher performance device drviers (2015-08-01).
-
+	  for use in higher performance device drivers (2015-08-01).
+	* drivers/net/slip.c:  Fix another compilation error (2015-08-02).

drivers/net/slip.c

@@ -405,8 +405,7 @@ static int slip_transmit(FAR struct slip_driver_s *priv)
  *   callback from devif_poll().  devif_poll() may be called:
  *
  *   1. When the preceding TX packet send is complete, or
- *   2. When the preceding TX packet send times o ]ut and the interface is reset
- *   3. During normal TX polling
+ *   2. During normal periodic polling
  *
  * Parameters:
  *   dev  - Reference to the NuttX driver state structure
@@ -506,16 +505,22 @@ static void slip_txtask(int argc, FAR char *argv[])
           flags = net_lock();
           priv->dev.d_buf = priv->txbuf;
 
+          /* Has a half second elapsed since the last timer poll? */
+
           msec_now = clock_systimer() * MSEC_PER_TICK;
           hsec = (unsigned int)(msec_now - msec_start) / (MSEC_PER_SEC / 2);
           if (hsec)
             {
+              /* Yes, perform the timer poll */
+
               (void)devif_timer(&priv->dev, slip_txpoll, hsec);
               msec_start += hsec * (MSEC_PER_SEC / 2);
             }
           else
             {
-              (void)devif_poll(&priv->dev, slip_uiptxpoll);
+              /* No, perform the normal TX poll */
+
+              (void)devif_poll(&priv->dev, slip_txpoll);
             }
 
           net_unlock(flags);

sched/semaphore/sem_tickwait.c

@@ -136,7 +136,7 @@ int sem_tickwait(FAR sem_t *sem, uint32_t start, uint32_t delay)
   /* Adjust the delay for any time since the delay was calculated */
 
   elapsed = clock_systimer() - start;
-  if (elapsed >= (UINT32_MAX / 2) || elapsed >= delay)
+  if (/*elapsed >= (UINT32_MAX / 2) || */ elapsed >= delay)
     {
       ret = -ETIMEDOUT;
       goto errout_with_irqdisabled;