arm: v4.18-rc5 with cpuidle on TC2 (A7 boot) spectre v2 issue

[Dietmar Eggemann]

Hi,

running v4.18-rc5 (plus still missing "power: vexpress: fix corruption 
in notifier registration", otherwise I get this rcu_sched stall issue) 
on TC2 (A7 boot) with vanilla multi_v7_defconfig plus 
CONFIG_ARM_BIG_LITTLE_CPUIDLE=y gives me continuous:

...
 CPUX: Spectre v2: incorrect context switching function, system vulnerable
...

messages.

Work around is to disable CONFIG_HARDEN_BRANCH_PREDICTOR.

-- Dietmar