dt-bindings: clock: spacemit: Add spacemit,k1-pll

Add definition for the PLL found on SpacemiT K1 SoC, which takes the
external 24MHz oscillator as input and generates clocks in various
frequencies for the system.

Signed-off-by: Haylen Chu <heylenay@4d2.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Alex Elder <elder@riscstar.com>
Reviewed-by: Yixun Lan <dlan@gentoo.org>
Link: https://lore.kernel.org/r/20250416135406.16284-3-heylenay@4d2.org


Signed-off-by: Yixun Lan <dlan@gentoo.org>