mfd: rohm-bd9576: Constify read-only regmap structs

`bd957x_regmap`, `bd9576_irqs` and `bd9576_irq_chip` are not modified
and can be declared as const to move its data to a read-only section.

Signed-off-by: Javier Carrasco <[e-mail]>
Reviewed-by: Matti Vaittinen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/rohm-bd9576.c

···
 	.n_yes_ranges = ARRAY_SIZE(volatile_ranges),
 };
 
-static struct regmap_config bd957x_regmap = {
+static const struct regmap_config bd957x_regmap = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.volatile_table = &volatile_regs,
···
 	.cache_type = REGCACHE_MAPLE,
 };
 
-static struct regmap_irq bd9576_irqs[] = {
+static const struct regmap_irq bd9576_irqs[] = {
 	REGMAP_IRQ_REG(BD9576_INT_THERM, 0, BD957X_MASK_INT_MAIN_THERM),
 	REGMAP_IRQ_REG(BD9576_INT_OVP, 0, BD957X_MASK_INT_MAIN_OVP),
 	REGMAP_IRQ_REG(BD9576_INT_SCP, 0, BD957X_MASK_INT_MAIN_SCP),
···
 	REGMAP_IRQ_REG(BD9576_INT_SYS, 0, BD957X_MASK_INT_MAIN_SYS),
 };
 
-static struct regmap_irq_chip bd9576_irq_chip = {
+static const struct regmap_irq_chip bd9576_irq_chip = {
 	.name = "bd9576_irq",
 	.irqs = &bd9576_irqs[0],
 	.num_irqs = ARRAY_SIZE(bd9576_irqs),