PCI/xgene-msi: Convert to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-pci@vger.kernel.org
Cc: Duc Dang <dhdang@apm.com>
Cc: rt@linuxtronix.de
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20161117183541.8588-8-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/cpuhotplug.h

@@ -38,6 +38,7 @@ enum cpuhp_state {
 	CPUHP_RADIX_DEAD,
 	CPUHP_PAGE_ALLOC_DEAD,
 	CPUHP_NET_DEV_DEAD,
+	CPUHP_PCI_XGENE_DEAD,
 	CPUHP_WORKQUEUE_PREP,
 	CPUHP_POWER_NUMA_PREPARE,
 	CPUHP_HRTIMERS_PREPARE,