ARM: dts: qcom: msm8974-klte: Add support for touchkey

Add support for the touchkey found on the Samsung Galaxy S5. The
touchkey is responsible for handling the application and back buttons
found around the home button.

Signed-off-by: Iskren Chernev <iskren.chernev@gmail.com>
Link: https://lore.kernel.org/r/20200920144859.813032-3-iskren.chernev@gmail.com


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>