dt-bindings: input: qpnp-power-on: Add qcom,log-kpd-event description

Add support 'qcom,log-kpd-event' property which when enabled causes
KPDPWR status to be logged during driver INIT and runtime when key
is pressed.

Change-Id: Ib7b78bc602d84262e107de3d346a9e3307e2a9be

bindings/input/qpnp-power-on.txt

@@ -118,6 +118,8 @@ Optional properties:
 				power off trigger during system shutdown case.
 - qcom,ps-hold-hard-reset-disable:	Boolean property to disable PS_HOLD
 				power off trigger during system hard reset case.
+- qcom,log-kpd-event:		Boolean property to enable logging of KPDPWR status
+				during driver INIT and runtime when key is pressed.
 
 Optional Sub-nodes:
 - qcom,pon_1 ... qcom,pon_n:	These PON child nodes correspond to features