s2ram procedure used RAM magic word for marking suspend-to-RAM. This
method may not work in some cases, e.g. when global reset does not
reset RAM content. In that case resuming from s2ram is detected when
global reset occurred.
RAM magic word method is the default but with
CONFIG_PM_S2RAM_CUSTOM_MARKING a custom implementation can be provided.
Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>