greybus: arche-platform: ensure wake-detect pin is deasserted

During DB3.5 bringup, it was noted that wake_detect signal was not
properly generating SVC edge IRQ.  To ensure signal goes from low
to high correctly, let's bring signal low (regardless of default
pin state).

Testing Done:
- Used for DB3.5/EVT1.5 hardware during bringup
- Regression tested on DB3.1+ES2, DB3.1+ES3

Signed-off-by: Michael Scott <michael.scott@linaro.org>
Reviewed-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Tested-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>