ARM: shmobile: r8a7740: move r8a7740_init_irq_of() to setup

This patch moves r8a7740_init_irq_of() to setup code,
and remove intc-r8a7740

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>