mtd: nand: denali: use managed devm_irq_request()

Use the managed variant instead of request_irq() and free_irq().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>