ARM: dts: qcom: msm8974-FP2: Add support for touchscreen

Configure the touchscreen found on the new display module of the FP2.
To add some detail, FP2 has two different screen/touchscreen variants
("display module"), the old module has Synaptics touchscreen, the new
one this Ilitek touchscreen.

We're only supporting the new display module for now.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220421214243.352469-1-luca@z3ntu.xyz