arm64: dts: qcom: msm8998-fxtec-pro1: Add tlmm keyboard keys

This device has a physical matrix keyboard, connected to a GPIO
expander, for which there's still no support yet.
Though, some of the keys are connected to the MSM8998 GPIOs and not
as a matrix, so these can be added.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210909123823.368199-4-angelogioacchino.delregno@somainline.org