wlcore: Add support for optional wakeirq

Now with wlcore using PM runtime, we can also add support for Linux
generic wakeirq handling for it if configured in the dts file.

The wakeirq can be configured as the second interrupt in the dts file
with interrupts-extended property where it is the padconf irq of the OOB
GPIO pin used for wlcore interrupt.

Note that eventually we should also allow configuring wlcore to use the
SDIO dat1 IRQ for wake-up, and in that case the the wakeirq should be
configured to be the padconf interrupt of the dat1 pin and not the
padconf interrupt of the OOB GPIO pin.

Cc: Eyal Reizer <eyalr@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>