arm64: dts: qcom: sc7280: Add touchscreen to villager

This adds the touchscreen to the sc7280-herobrine-villager device
tree. Note that the touchscreen on villager actually uses the reset
line and thus we use the more specific "elan,ekth6915" compatible
which allows us to specify the reset.

The fact that villager's touchscreen uses the reset line can be
contrasted against the touchscreen for CRD/herobrine-r1. On those
boards, even though the touchscreen goes to the display, it's not
hooked up to anything there.

In order to keep the line parked on herobrine/CRD, we'll move the
pullup from the qcard.dtsi file to the specific boards. This allows us
to disable the pullup in the villager device tree since the pin is an
output.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220524134840.1.I80072b8815ac08c12af8f379a33cc2d83693dc51@changeid