Add MT7981 clock dt-bindings, include topckgen, apmixedsys,
infracfg, and ethernet subsystem clocks.
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
Signed-off-by: Jianhui Zhao <zhaojh329@xxxxxxxxx>
Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>