irqchip/exynos-combiner: Switch to raw_spinlock

irqchip/exynos-combiner: Switch to raw_spinlock

The exynos-combiner driver uses a regular spinlock to protect access to
the combiner interrupt status register in combiner_handle_cascade_irq(),
which is invoked in hard interrupt context as a chained interrupt handler.

When PREEMPT_RT is enabled on ARM, regular spinlock is converted to a
sleeping lock (mutex-based), which must not be used in atomic context
such as hard interrupt handlers.

Switch the irq_controller_lock to raw_spinlock, which remains a true
non-sleeping spinlock even under PREEMPT_RT.

Fixes: a900e5d99718 ("ARM: exynos: move exynos4210-combiner to drivers/irqchip")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>