irqchip: s3c24xx: add irq_set_type callback for basic interrupt types

Enables post-init setting of the desired typehandler for the interrupt.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>