clk: sunxi-ng: sun50i: a64: Use sigma-delta modulation for audio PLL
The audio blocks require specific clock rates. Until now we were using
the closest clock rate possible with integer N-M factors. This resulted
in audio playback being slightly slower than it should be.
The vendor kernel gets around this (for some SoCs) by using sigma-delta
modulation to generate a fractional-N factor. As the PLL hardware is
identical in most chips, we can port the settings for H3 onto the A64.