regulator: pfuze100: add fsl,pmic-stby-poweroff property

Document the new optional "fsl,pmic-stby-poweroff" property.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/pfuze100.txt

@@ -12,6 +12,11 @@ Optional properties:
   disabled. This binding is a workaround to keep backward compatibility with
   old dtb's which rely on the fact that the switched regulators are always on
   and don't mark them explicit as "regulator-always-on".
+- fsl,pmic-stby-poweroff: if present, configure the PMIC to shutdown all
+  power rails when PMIC_STBY_REQ line is asserted during the power off sequence.
+  Use this option if the SoC should be powered off by external power
+  management IC (PMIC) on PMIC_STBY_REQ signal.
+  As opposite to PMIC_STBY_REQ boards can implement PMIC_ON_REQ signal.
 
 Required child node:
 - regulators: This is the list of child nodes that specify the regulator