dt-bindings: embedded-controller: Add Lenovo Thinkpad T14s EC

dt-bindings: embedded-controller: Add Lenovo Thinkpad T14s EC

Add binding for the EC found in the Thinkpad T14s Gen6 Snapdragon,
which is based on the Qualcomm X1 Elite. Some of the system LEDs
and extra keys are only accessible via the EC.

Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20250918-thinkpad-t14s-ec-v5-1-ac0bc6382c5c@collabora.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>