pinctrl: baytrail: Add missing spinlock usage in byt_gpio_irq_handler

According to VLI64 Intel Atom E3800 Specification Update (#329901)
concurrent read accesses may result in returning 0xffffffff and write
accesses may be dropped silently.
To workaround all accesses must be protected by locks.

Cc: [email protected]
Signed-off-by: Alexander Stein <[email protected]>
Acked-by: Mika Westerberg <[email protected]>
Signed-off-by: Linus Walleij <[email protected]>

drivers/pinctrl/intel/pinctrl-baytrail.c

@@ -1623,7 +1623,9 @@ static void byt_gpio_irq_handler(struct irq_desc *desc)
 			continue;
 		}
 
+		raw_spin_lock(&vg->lock);
 		pending = readl(reg);
+		raw_spin_unlock(&vg->lock);
 		for_each_set_bit(pin, &pending, 32) {
 			virq = irq_find_mapping(vg->chip.irqdomain, base + pin);
 			generic_handle_irq(virq);