dt-bindings: timer: Add missing compatibles

Newer Allwinner SoCs have different number of interrupts, let's add
different compatibles for all of them to deal with this properly.

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>