dt-bindings: regulator: add LS2 load switch documentation

Document device-tree settings of the load-switch LS2
in the tps65218 device.

Signed-off-by: Christian Hohnstaedt <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/regulator/tps65218.txt

···
 		regulator-always-on;
 	};
 
+	ls2: regulator-ls2 {
+		regulator-min-microamp = <100000>;
+		regulator-max-microamp = <1000000>;
+	};
+
 	ls3: regulator-ls3 {
 		regulator-min-microvolt = <100000>;
 		regulator-max-microvolt = <1000000>;