regmap-irq: handle const struct regmap_irq_sub_irq_map

The struct instances supplied by the drivers are never modified.
Handle them as const in the regmap core allowing the drivers to put them
into .rodata.

Also add a new entry to const_structs.checkpatch to make sure future
instances of this struct already enter the tree as const.

Signed-off-by: Thomas Weißschuh <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

drivers/base/regmap/regmap-irq.c

···
 					   unsigned int b)
 {
 	const struct regmap_irq_chip *chip = data->chip;
+	const struct regmap_irq_sub_irq_map *subreg;
 	struct regmap *map = data->map;
-	struct regmap_irq_sub_irq_map *subreg;
 	unsigned int reg;
 	int i, ret = 0;
 

include/linux/regmap.h

···
 
 	unsigned int main_status;
 	unsigned int num_main_status_bits;
-	struct regmap_irq_sub_irq_map *sub_reg_offsets;
+	const struct regmap_irq_sub_irq_map *sub_reg_offsets;
 	int num_main_regs;
 
 	unsigned int status_base;

scripts/const_structs.checkpatch

···
 regmap_config
 regmap_irq
 regmap_irq_chip
+regmap_irq_sub_irq_map
 regmap_range
 regmap_range_cfg
 regulator_ops