arm: omap: irq: drop omap3_intc_handle_irq()

now that we're calling set_handle_irq() from
init_irq(), we can safely drop all callers to
omap3_intc_handle_irq() and its definition.

Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>