regulator: dt-bindings: samsung,s5m8767: correct s5m8767,pmic-buck-default-dvs-idx property

The driver was always parsing "s5m8767,pmic-buck-default-dvs-idx", not
"s5m8767,pmic-buck234-default-dvs-idx".

Cc: <stable@vger.kernel.org>
Fixes: 26aec009 ("regulator: add device tree support for s5m8767")
Signed-off-by: NKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: NRob Herring <robh@kernel.org>
Message-Id: <20211008113723.134648-3-krzysztof.kozlowski@canonical.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/samsung,s5m8767.txt

@@ -39,7 +39,7 @@ Optional properties of the main device node (the parent!):
 
 Additional properties required if either of the optional properties are used:
 
- - s5m8767,pmic-buck234-default-dvs-idx: Default voltage setting selected from
+ - s5m8767,pmic-buck-default-dvs-idx: Default voltage setting selected from
    the possible 8 options selectable by the dvs gpios. The value of this
    property should be between 0 and 7. If not specified or if out of range, the
    default value of this property is set to 0.