genirq/PM: Unexport {suspend,resume}_device_irqs()

Ever since {suspend,resume}_device_irqs() were introduced in 2009
by commit 0a0c516 ("PM: Introduce functions for suspending and
resuming device interrupts"), they've been exported even though there
are no module users and never will be:  The functions are solely called
by the PM core, which is always built-in.  Unexport them.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/fad9b50609f9d9828ea14772dbd4d195713f1c4b.1654846687.git.lukas@wunner.de

kernel/irq/pm.c

@@ -147,7 +147,6 @@ void suspend_device_irqs(void)
 			synchronize_irq(irq);
 	}
 }
-EXPORT_SYMBOL_GPL(suspend_device_irqs);
 
 static void resume_irq(struct irq_desc *desc)
 {
@@ -259,4 +258,3 @@ void resume_device_irqs(void)
 {
 	resume_irqs(false);
 }
-EXPORT_SYMBOL_GPL(resume_device_irqs);