modules: hal_nordic: nrfs: dvfs: Deprecate Kconfig option

Deprecate NRFS_LOCAL_DOMAIN_DVFS_SCALE_DOWN_AFTER_INIT option for
scaling down CPU frequency during dvfs handler initialization.
Clock control API is managing access to DVFS and DVFS should not
be controlled bypassing this API. Deprecated feature will be added in
the clock control.

Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>