mfd/regulator: dt-bindings: max77686: Document regulators off in suspend

Add information which regulators can be disabled during system suspend.
Suggested-by: NJavier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: NKrzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/mfd/max77686.txt

@@ -34,6 +34,12 @@ to get matched with their hardware counterparts as follow:
 	-BUCKn 	:	for BUCKs, where n can lie in range 1 to 9.
 			example: BUCK1, BUCK5, BUCK9.
 
+  Regulators which can be turned off during system suspend:
+	-LDOn	:	2, 6-8, 10-12, 14-16,
+	-BUCKn	:	1-4.
+  Use standard regulator bindings for it ('regulator-off-in-suspend').
+
+
 Example:
 
 	max77686@09 {