ARM: orion5x: switch to DT interrupts and timer

ARM: orion5x: switch to DT interrupts and timer

This commit switches the Orion5x platforms described through DT to use
a DT-defined interrupt controller and timer.

This involves:

 * Describing in the DT the bridge interrupt controller, which is a
   child interrupt controller to the main one, which is used for timer
   and watchdog interrupts.

 * Describing in the DT the timer.

 * Adding in the DT the interrupt specifications for the watchdog.

 * Selecting the ORION_IRQCHIP and ORION_TIMER drivers to be compiled.

 * Change board-dt.c to no longer have an ->init_time() callback,
   since the default callback will work fine: it calls
   clocksource_of_init() and of_clk_init(), as needed.

 * Implement a multi-IRQ handler for non-DT platforms in
   mach-orion5x/irq.c.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Link: https://lkml.kernel.org/r/1398202002-28530-24-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>