mfd: max77686: Don't suggest in binding to use a deprecated property

The regulator-compatible property from the regulator DT binding was
deprecated. But the max77686 DT binding doc still suggest to use it
instead of the regulator node name's which is the correct approach.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/mfd/max77686.txt

@@ -26,7 +26,7 @@ Optional node:
 	};
 	refer Documentation/devicetree/bindings/regulator/regulator.txt
 
-  The regulator-compatible property of regulator should initialized with string
+  The regulator node's name should be initialized with a string
 to get matched with their hardware counterparts as follow:
 
 	-LDOn 	:	for LDOs, where n can lie in range 1 to 26.
@@ -55,16 +55,14 @@ Example:
 		reg = <0x09>;
 
 		voltage-regulators {
-			ldo11_reg {
-				regulator-compatible = "LDO11";
+			ldo11_reg: LDO11 {
 				regulator-name = "vdd_ldo11";
 				regulator-min-microvolt = <1900000>;
 				regulator-max-microvolt = <1900000>;
 				regulator-always-on;
 			};
 
-			buck1_reg {
-				regulator-compatible = "BUCK1";
+			buck1_reg: BUCK1 {
 				regulator-name = "vdd_mif";
 				regulator-min-microvolt = <950000>;
 				regulator-max-microvolt = <1300000>;
@@ -72,8 +70,7 @@ Example:
 				regulator-boot-on;
 			};
 
-			buck9_reg {
-				regulator-compatible = "BUCK9";
+			buck9_reg: BUCK9 {
 				regulator-name = "CAM_ISP_CORE_1.2V";
 				regulator-min-microvolt = <1000000>;
 				regulator-max-microvolt = <1200000>;