atm: nicstar: Replace spin_is_locked() with spin_trylock()

ns_poll() used spin_is_locked() + spin_lock() to get achieve the same
thing as a spin_trylock(), so simplify it by using that instead. This is
also a step towards possibly removing spin_is_locked().
Signed-off-by: Lance Roy <ldr709@gmail.com>
Cc: Chas Williams <3chas3@gmail.com>
Cc: <linux-atm-general@lists.sourceforge.net>
Cc: <netdev@vger.kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/atm/nicstar.c

@@ -2689,11 +2689,10 @@ static void ns_poll(struct timer_list *unused)
 	PRINTK("nicstar: Entering ns_poll().\n");
 	for (i = 0; i < num_cards; i++) {
 		card = cards[i];
-		if (spin_is_locked(&card->int_lock)) {
+		if (!spin_trylock_irqsave(&card->int_lock, flags)) {
 			/* Probably it isn't worth spinning */
 			continue;
 		}
-		spin_lock_irqsave(&card->int_lock, flags);
 
 		stat_w = 0;
 		stat_r = readl(card->membase + STAT);