regmap-irq: Deprecate the not_fixed_stride flag

This flag is a bit of a hack and the same thing can be accomplished
using a custom ->get_irq_reg() callback. Add a warning to catch any
use of the flag.
Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Link: https://lore.kernel.org/r/20220623211420.918875-13-aidanmacdonald.0x0@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/base/regmap/regmap-irq.c

@@ -739,6 +739,8 @@ int regmap_add_irq_chip_fwnode(struct fwnode_handle *fwnode,
 	}
 
 	if (chip->not_fixed_stride) {
+		dev_warn(map->dev, "not_fixed_stride is deprecated; use ->get_irq_reg() instead");
+
 		for (i = 0; i < chip->num_regs; i++)
 			if (chip->sub_reg_offsets[i].num_regs != 1)
 				return -EINVAL;

include/linux/regmap.h

@@ -1510,7 +1510,9 @@ struct regmap_irq_chip_data;
  *                   set when they were masked.
  * @not_fixed_stride: Used when chip peripherals are not laid out with fixed
  *		      stride. Must be used with sub_reg_offsets containing the
- * 		      offsets to each peripheral.
+ *		      offsets to each peripheral. Deprecated; the same thing
+ *		      can be accomplished with a @get_irq_reg callback, without
+ *		      the need for a @sub_reg_offsets table.
  * @status_invert: Inverted status register: cleared bits are active interrupts.
  * @runtime_pm:  Hold a runtime PM lock on the device when accessing it.
  *