dt-bindings: mfd: qcom,tcsr: Document ipq6018 compatible

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/mfd/qcom,tcsr.txt

@@ -6,6 +6,7 @@ registers via syscon.
 
 Required properties:
 - compatible:	Should contain:
+		"qcom,tcsr-ipq6018", "syscon", "simple-mfd" for IPQ6018
 		"qcom,tcsr-ipq8064", "syscon" for IPQ8064
 		"qcom,tcsr-apq8064", "syscon" for APQ8064
 		"qcom,tcsr-msm8660", "syscon" for MSM8660