irqchip: Gic: fix boot for chained gics

As of c0114709: "irqchip: gic: Perform the gic_secondary_init() call
via CPU notifier", booting on a platform with chained gics (e.g.
Realview EB ARM11MPCore) will result in the gic_cpu_notifier being
registered twice, corrupting the cpu notifier list and rendering the
platform unbootable.

This patch ensures that we only register the notifier for the first
gic, allowing platforms with chained gics to boot. At the same time we
limit the pointlessly duplicated calls to set_smp_cross_call and
set_handle_irq to the first gic registered.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: marc.zyngier@arm.com
Cc: rob.herring@calxeda.com
Cc: olof@lixom.net
Link: http://lkml.kernel.org/r/1385648500-29048-1-git-send-email-mark.rutland@arm.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/irqchip/irq-gic.c

@@ -814,12 +814,13 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
 	if (WARN_ON(!gic->domain))
 		return;
 
+	if (gic_nr == 0) {
 #ifdef CONFIG_SMP
 		set_smp_cross_call(gic_raise_softirq);
 		register_cpu_notifier(&gic_cpu_notifier);
 #endif
-
 		set_handle_irq(gic_handle_irq);
+	}
 
 	gic_chip.flags |= gic_arch_extn.flags;
 	gic_dist_init(gic);