ARM: orion: simplify orion_ge00_switch_init

One of the last users of NO_IRQ on ARM is the switch initialization
code on orion5x, which sometimes passes a GPIO based IRQ number.

However, the driver doesn't actually use this number, and according
to Andrew Lunn never will do it for non-DT based machines, so
we can simply drop the irq argument.

Simplifying it further, we can also drop the static platform_device
and instead call platform_device_register_data(), which in turn
lets us mark the platform_data structures as __initdata and slightly
reduce the memory consumption.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>