irqchip: davinci-cp-intc: move the driver to drivers/irqchip

The cp-intc driver has now been cleaned up. Move it to drivers/irqchip
where it belongs.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>