mISDN: replace current->state by set_current_state()

Use helper function to access current->state.
Direct assignments are prone to races and therefore buggy.

Thanks to Peter Zijlstra for the exact definition of the problem.
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/isdn/hardware/mISDN/hfcpci.c

@@ -1755,7 +1755,7 @@ init_card(struct hfc_pci *hc)
 		enable_hwirq(hc);
 		spin_unlock_irqrestore(&hc->lock, flags);
 		/* Timeout 80ms */
-		current->state = TASK_UNINTERRUPTIBLE;
+		set_current_state(TASK_UNINTERRUPTIBLE);
 		schedule_timeout((80 * HZ) / 1000);
 		printk(KERN_INFO "HFC PCI: IRQ %d count %d\n",
 		       hc->irq, hc->irqcnt);