irqchip: omap-intc: Remove unused legacy interface for omap2

Nowadays omap2 is booting in device tree only mode so there is no
need to keep the legacy interface around for omap2_init_irq().

Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1421187806-6804-3-git-send-email-tony@atomide.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>