arm64: dts: qcom: msm8916-samsung-serranove: Add touch screen

Like msm8916-samsung-a3u-eur, the S4 Mini VE uses a Zinitix BT541
touch screen. Add it together with the necessary fixed-regulator
to the device tree.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211004201921.18526-3-stephan@gerhold.net