mfd: retu: Constify read-only regmap structs

The regmap_bus, regmap_irq and regmap_irq_chip structs are not modified
and can be declared as const to move their data to a read-only section.

The pointer to reference the regmap_irq_chip structs has been converted
to const.
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20240704-mfd-const-regmap_config-v2-11-0c8785b1331d@gmail.comSigned-off-by: Lee Jones <lee@kernel.org>

drivers/mfd/retu-mfd.c

@@ -65,13 +65,13 @@ static const struct mfd_cell retu_devs[] = {
 	}
 };
 
-static struct regmap_irq retu_irqs[] = {
+static const struct regmap_irq retu_irqs[] = {
 	[RETU_INT_PWR] = {
 		.mask = 1 << RETU_INT_PWR,
 	}
 };
 
-static struct regmap_irq_chip retu_irq_chip = {
+static const struct regmap_irq_chip retu_irq_chip = {
 	.name		= "RETU",
 	.irqs		= retu_irqs,
 	.num_irqs	= ARRAY_SIZE(retu_irqs),
@@ -101,13 +101,13 @@ static const struct mfd_cell tahvo_devs[] = {
 	},
 };
 
-static struct regmap_irq tahvo_irqs[] = {
+static const struct regmap_irq tahvo_irqs[] = {
 	[TAHVO_INT_VBUS] = {
 		.mask = 1 << TAHVO_INT_VBUS,
 	}
 };
 
-static struct regmap_irq_chip tahvo_irq_chip = {
+static const struct regmap_irq_chip tahvo_irq_chip = {
 	.name		= "TAHVO",
 	.irqs		= tahvo_irqs,
 	.num_irqs	= ARRAY_SIZE(tahvo_irqs),
@@ -120,7 +120,7 @@ static struct regmap_irq_chip tahvo_irq_chip = {
 static const struct retu_data {
 	char			*chip_name;
 	char			*companion_name;
-	struct regmap_irq_chip	*irq_chip;
+	const struct regmap_irq_chip	*irq_chip;
 	const struct mfd_cell	*children;
 	int			nchildren;
 } retu_data[] = {
@@ -216,7 +216,7 @@ static int retu_regmap_write(void *context, const void *data, size_t count)
 	return i2c_smbus_write_word_data(i2c, reg, val);
 }
 
-static struct regmap_bus retu_bus = {
+static const struct regmap_bus retu_bus = {
 	.read = retu_regmap_read,
 	.write = retu_regmap_write,
 	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,