arm64: dts: qcom: msm8996-xiaomi-scorpio: Add touchkey controller

Add a node and pin states for Cypress StreetFighter touchkey
controller.

Signed-off-by: Yassine Oudjana <y.oudjana@protonmail.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211104104932.104046-1-y.oudjana@protonmail.com