arm64: dts: qcom: pms405: calibrate the VADC correctly

Set the qcom,ratiometric property to make the VADC use the VDD reference
(1.875V) and GND for channel calibration of the temperature channels
instead of 1.25V. Allow a 200us delay between the AMUX configuration and
ADC starting conversion using qcom,hw-settle-time as described in
documentation.

Fixes: 041b9a7b ("arm64: dts: pms405: Export PMIC temperature to thermal framework")
Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>