rtc: rtc-pm8xxx: Add support for pm8018 rtc

In order to support RTC on Qualcomm MDM9615 SoC, add support for
the pm8018 rtc in rtc-pm8xxx driver.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/mfd/qcom-pm8xxx.txt

@@ -62,6 +62,7 @@ The below bindings specify the set of valid subnodes.
 		    "qcom,pm8058-rtc"
 		    "qcom,pm8921-rtc"
 		    "qcom,pm8941-rtc"
+		    "qcom,pm8018-rtc"
 
 - reg:
 	Usage: required