arm64: dts: qcom: x1e80100-t14s: add EC

arm64: dts: qcom: x1e80100-t14s: add EC

Describe ThinkPad Embedded Controller in the T14s device tree,
which adds LED and special key support.

Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on Thinkpad T14S OLED
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Link: https://patch.msgid.link/20250918-thinkpad-t14s-ec-v5-3-ac0bc6382c5c@collabora.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>