genirq/chip: Constify the 'chip' field in irq_data

Commit 393e1280f765 ("genirq: Allow irq_chip registration functions to take
a const irq_chip") and ef6e5d61eb7a ("genirq: Allow
irq_set_chip_handler_name_locked() to take a const irq_chip") have
introduced some ugly casting to store some const parameters into non-const
struct members. [1] [2]

Correctly constify this 'chip' field in struct irq_data, update
corresponding asseccors and remove the now useless cast in
irq_set_chip_handler_name_locked() and irq_set_chip().

[1]: https://elixir.bootlin.com/linux/v7.1-rc5/source/kernel/irq/chip.c#L48
[2]: https://elixir.bootlin.com/linux/v7.1-rc5/source/include/linux/irqdesc.h#L250

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/41b4818e14f2f6e6a7406751d65b59899bd40331.1780343698.git.christophe.jaillet@wanadoo.fr