gpio: Emma Mobile GPIO driver V2

This patch is V2 of the Emma Mobile GPIO driver. This
driver is designed to be reusable between multiple SoCs
that share the same basic building block, but so far it
has only been used on Emma Mobile EV2.

Each driver instance handles 32 GPIOs with individually
maskable IRQs. The driver operates on two I/O memory
ranges and the 32 GPIOs are hooked up to two interrupts.

In the case of Emma Mobile EV2 this GPIO building block
is used as main external interrupt controller hooking up
159 GPIOS as 159 interrupts via 5 driver instances and
10 interrupts to the GIC and the Cortex-A9 Dual.

Signed-off-by: Magnus Damm <damm@opensource.se>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>