PM8916 has one vibration motor driver that is already supported
by the pm8xxx-vibrator driver.

Add a node describing it to pm8916.dtsi.
Keep it disabled by default since not all devices make use of it.
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20191211192906.56638-1-stephan@gerhold.netSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>