genirq: Allow irq_set_chip_handler_name_locked() to take a const irq_chip

Similar to commit 393e1280 ("genirq: Allow irq_chip registration
functions to take a const irq_chip"), allow the
irq_set_chip_handler_name_locked() function to take a const irq_chip
argument.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220706151553.1580790-1-michael@walle.cc