irqchip/gic-v3-its: Don't enable interrupts in its_irq_set_vcpu_affinity()

In the Linux kernel, the following vulnerability has been resolved:

irqchip/gic-v3-its: Don't enable interrupts in its_irq_set_vcpu_affinity()

The following call-chain leads to enabling interrupts in a nested interrupt

disabled section:

irq_set_vcpu_affinity()

irq_get_desc_lock()

raw_spin_lock_irqsave() <--- Disable interrupts

its_irq_set_vcpu_affinity()

guard(raw_spinlock_irq) <--- Enables interrupts when leaving the guard()

irq_put_desc_unlock() <--- Warns because interrupts are enabled

This was broken in commit b97e8a2f7130, which replaced the original

raw_spin_[un]lock() pair with guard(raw_spinlock_irq).

Fix the issue by using guard(raw_spinlock).

[ tglx: Massaged change log ]