dt-bindings: clock: spacemit: introduce i2s pre-clock to fix i2s clock

Previously, the K1 clock driver did not include the parent clocks of
the I2S sysclk.

Introduce pre-clock to fix I2S clock.

Otherwise, the I2S clock may not work as expected.

This patch adds their definitions to allow proper registration
in the driver and usage in the device tree.

Fixes: 1b72c59db0add ("clk: spacemit: Add clock support for SpacemiT K1 SoC")
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>