mfd: bd9571mwv: Constify struct regmap_irq_chip

`bd9571mwv_irq_chip` and `bd9574mwf_irq_chip` are not modified and can
be declared as const to move their 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/bd9571mwv.c

···
 		       BD9571MWV_INT_INTREQ_BKUP_TRG_INT),
 };
 
-static struct regmap_irq_chip bd9571mwv_irq_chip = {
+static const struct regmap_irq_chip bd9571mwv_irq_chip = {
 	.name		= "bd9571mwv",
 	.status_base	= BD9571MWV_INT_INTREQ,
 	.mask_base	= BD9571MWV_INT_INTMASK,
···
 	.max_register	= 0xff,
 };
 
-static struct regmap_irq_chip bd9574mwf_irq_chip = {
+static const struct regmap_irq_chip bd9574mwf_irq_chip = {
 	.name		= "bd9574mwf",
 	.status_base	= BD9571MWV_INT_INTREQ,
 	.mask_base	= BD9571MWV_INT_INTMASK,