drivers: irqchip: add PDC irqdomain for wakeup capable GPIOs

Introduce a new domain for wakeup capable GPIOs. The domain can be
requested using the bus token DOMAIN_BUS_WAKEUP. In the following
patches, we will specify PDC as the wakeup-parent for the TLMM GPIO
irqchip. Requesting a wakeup GPIO will setup the GPIO and the
corresponding PDC interrupt as its parent.

Change-Id: Ie3823f5c7823cfb245e5f73f254f7fd00aa2c279
Patch-mainline: https://lore.kernel.org/patchwork/patch/1026602


Co-developed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Lina Iyer <ilina@codeaurora.org>