mfd: tps65218: Constify struct regmap_irq_chip

`tps65218_irq_chip` is not modified and can be declared as const to
move its data to a read-only section.
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20240704-mfd-const-regmap_config-v2-17-0c8785b1331d@gmail.comSigned-off-by: Lee Jones <lee@kernel.org>

drivers/mfd/tps65218.c

@@ -186,7 +186,7 @@ static const struct regmap_irq tps65218_irqs[] = {
 	},
 };
 
-static struct regmap_irq_chip tps65218_irq_chip = {
+static const struct regmap_irq_chip tps65218_irq_chip = {
 	.name = "tps65218",
 	.irqs = tps65218_irqs,
 	.num_irqs = ARRAY_SIZE(tps65218_irqs),