irqchip/ath79-misc: Move the MISC driver from arch/mips/ath79/

The driver stays the same but the initialization changes a bit.
For OF boards we now get the memory map from the OF node and use
a linear mapping instead of the legacy mapping. For legacy boards
we still use a legacy mapping and just pass down all the parameters
from the board init code.

Signed-off-by: Alban Bedel <albeu@free.fr>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1453553867-27003-1-git-send-email-albeu@free.fr


Signed-off-by: Jason Cooper <jason@lakedaemon.net>