powerpc/85xx: remove setup_irq(NULL action) in ksi8560

setup_irq(0, NULL) is broken as setup_irq() dereferences action
unconditionally.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/platforms/85xx/ksi8560.c

@@ -106,8 +106,6 @@ static void __init ksi8560_pic_init(void)
 	cpm2_pic_init(np);
 	of_node_put(np);
 	set_irq_chained_handler(irq, cpm2_cascade);
-
-	setup_irq(0, NULL);
 #endif
 }