pinctrl: armada-37xx: make irq_lock a raw spinlock to avoid invalid wait context

The irqchip->irq_set_type method is called by __irq_set_trigger() under
the desc->lock raw spinlock.

The armada-37xx implementation, armada_37xx_irq_set_type(), takes a
plain spinlock, the kind that becomes sleepable on RT.

Therefore, this is an invalid locking scheme for which we get a kernel
splat stating just that ("[ BUG: Invalid wait context ]"), because the
context in which the plain spinlock may sleep is atomic due to the raw
spinlock. We need to go raw spinlocks all the way.

Replace the driver's irq_lock with a raw spinlock, to disable preemption
even on RT.

Cc: <stable@vger.kernel.org> # 5.15+
Fixes: 2f227605

 ("pinctrl: armada-37xx: Add irqchip support")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20220716233745.1704677-2-vladimir.oltean@nxp.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>