ARM: dts: sun8i: h3: beelink-x2: Add GPIO CEC node

Beelink X2 doesn't use HW CEC controller found in DW HDMI core. It has
dedicated GPIO pin for that purpose.

Add a node for it.

Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20211120102024.439456-1-jernej.skrabec@gmail.com