net/flowcache: Convert to hotplug state machine

Install the callbacks via the state machine. Use multi state support to avoid
custom list handling for the multiple instances.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: netdev@vger.kernel.org
Cc: rt@linutronix.de
Cc: "David S. Miller" <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20161103145021.28528-10-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 394eb7e..86b940f 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -56,6 +56,7 @@ enum cpuhp_state {
 	CPUHP_ARM_SHMOBILE_SCU_PREPARE,
 	CPUHP_SH_SH3X_PREPARE,
 	CPUHP_BLK_MQ_PREPARE,
+	CPUHP_NET_FLOW_PREPARE,
 	CPUHP_TIMERS_DEAD,
 	CPUHP_NOTF_ERR_INJ_PREPARE,
 	CPUHP_MIPS_SOC_PREPARE,