arm64: dts: qcom: sc7280: Hook up the touchscreen IO rail on evoker

On older revisions of evoker, the touchscreen was either
non-functional or needed special hardware magic to get it talking
properly. It's been decided that the proper way going forward is to
use L3C to power some buffers on the QCard and then configure the
touchscreens for 1.8V. Let's do that.

Note that this is safe to do even on older revs even if it might not
make the touchscreen work there (because they didn't have a properly
stuffed QCard). As talked about in the patch ("arm64: dts: qcom:
sc7280: On QCard, regulator L3C should be 1.8V") the L3C regulator
didn't go anywhere at all on older revs.

This patch relies on the patch ("HID: i2c-hid: goodix: Add
mainboard-vddio-supply") in order to function properly. Without that
patch this one won't do any harm but it won't actually accomplish its
goal.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230206184744.7.I2d960ed7f2445db0cf3d227fde985fbd740f3c4d@changeid