mfd: Add DT bindings for tps65917 PMIC

Add DT bindings for tps65917 PMIC.
Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

Documentation/devicetree/bindings/mfd/palmas.txt

@@ -6,6 +6,7 @@ twl6037 (palmas)
 tps65913 (palmas)
 tps65914 (palmas)
 tps659038
+tps65917
 
 Required properties:
 - compatible : Should be from the list
@@ -16,6 +17,7 @@ Required properties:
   ti,tps65914
   ti,tps80036
   ti,tps659038
+  ti,tps65917
 and also the generic series names
   ti,palmas
 - interrupt-controller : palmas has its own internal IRQs