power: reset: gpio-poweroff: add ability to specific active and inactive delays

Similar to gpio-reset allow to specify active and inactive delays
while keeping the 100ms defaults that were used previously all the time.

The dt-properties are named the same as in gpio-reset but get an "-ms"
suffix as properties should contain such a suffix specifying its unit.

Signed-off-by: Heiko Stuebner <heiko.stuebner@bq.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>