mfd: hi655x-pmic: Constify struct regmap_config

`hi655x_regmap_config` 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-v2-3-0c8785b1331d@gmail.comSigned-off-by: Lee Jones <lee@kernel.org>

drivers/mfd/hi655x-pmic.c

@@ -41,7 +41,7 @@ static const struct regmap_irq_chip hi655x_irq_chip = {
 	.mask_base = HI655X_IRQ_MASK_BASE,
 };
 
-static struct regmap_config hi655x_regmap_config = {
+static const struct regmap_config hi655x_regmap_config = {
 	.reg_bits = 32,
 	.reg_stride = HI655X_STRIDE,
 	.val_bits = 8,