mfd: sec: Enable wakeup from suspend via devicetree property

Set device wakeup capability from devicetree property (done by drivers
core), instead of always setting it to 0 (because value in platform data
is not assigned).

This should not have visible effect on actual resuming from suspend
because the child device - S5M RTC driver - is responsible for waking
up and sets device wakeup unconditionally.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>