Use __SPIN_LOCK_UNLOCKED to initialize bad_irq_desc.lock

SPIN_LOCK_UNLOCKED is deprecated as lockdep cannot properly work with
locks initialized with it.

This fix is necessary to compile the linux-rt tree for ARM.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>

arch/arm/kernel/irq.c

@@ -101,7 +101,7 @@ unlock:
 /* Handle bad interrupts */
 static struct irq_desc bad_irq_desc = {
 	.handle_irq = handle_bad_irq,
-	.lock = SPIN_LOCK_UNLOCKED
+	.lock = __SPIN_LOCK_UNLOCKED(bad_irq_desc.lock),
 };
 
 /*