dt-bindings: imx6q-clock: add new fsl,pmic-stby-poweroff property

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/clock/imx6q-clock.txt

@@ -6,6 +6,14 @@ Required properties:
 - interrupts: Should contain CCM interrupt
 - #clock-cells: Should be <1>
 
+Optional properties:
+- fsl,pmic-stby-poweroff: Configure CCM to assert PMIC_STBY_REQ signal
+  on power off.
+  Use this property if the SoC should be powered off by external power
+  management IC (PMIC) triggered via PMIC_STBY_REQ signal.
+  Boards that are designed to initiate poweroff on PMIC_ON_REQ signal should
+  be using "syscon-poweroff" driver instead.
+
 The clock consumer should specify the desired clock by having the clock
 ID in its "clocks" phandle cell.  See include/dt-bindings/clock/imx6qdl-clock.h
 for the full list of i.MX6 Quad and DualLite clock IDs.