Allwinner R40 has a timer.

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/20210510163647.2731675-1-jernej.skrabec@gmail.com