irqchip/renesas-rzg2l: Fix missing put_device

rzg2l_irqc_common_init() calls of_find_device_by_node(), but the
corresponding put_device() call is missing.  This also gets reported by
make coccicheck.

Make use of the cleanup interfaces from cleanup.h to call into
__free_put_device(), which in turn calls into put_device when leaving
function rzg2l_irqc_common_init() and variable "dev" goes out of scope.

To prevent that the device is put on successful completion, assign NULL to
"dev" to prevent __free_put_device() from calling into put_device() within
the successful path.

"make coccicheck" will still complain about missing put_device() calls,
but those are false positives now.

Fixes: 3fed0955 ("irqchip: Add RZ/G2L IA55 Interrupt Controller driver")
Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241011172003.1242841-1-fabrizio.castro.jz@renesas.com