of/irq: Replace of_irq with of_phandle_args

struct of_irq and struct of_phandle_args are exactly the same structure.
This patch makes the kernel use of_phandle_args everywhere. This in
itself isn't a big deal, but it makes some follow-on patches simpler.

Signed-off-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Michal Simek <monstr@monstr.eu>
Acked-by: Tony Lindgren <tony@atomide.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>