mfd: tps65219: Constify read-only regmap structs

`tps65219_irqs` and `tps65219_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 <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20240704-mfd-const-regmap_config-v2-18-0c8785b1331d@gmail.com


Signed-off-by: Lee Jones <lee@kernel.org>