dt-bindings: clock: mediatek: add mt7981 clock IDs

Add MT7981 clock dt-bindings, include topckgen, apmixedsys,
infracfg, and ethernet subsystem clocks.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Jianhui Zhao <zhaojh329@gmail.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Link: https://lore.kernel.org/r/e353d32b5a4481766519a037afe1ed44e31ece1a.1674703830.git.daniel@makrotopia.org


Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>