arm64: dts: allwinner: a64: add nodes necessary for analog sound support

Add nodes for i2s, digital and analog parts of audiocodec on A64.

The routing paths listed are entries connecting the digital and analog
side of the audio codec together. Due to how device tree works, these
must be copied over to each board device tree, in addition to any board
level routes.

The oversampling rate is set to 128, so that when playing back 192 kHz
audio samples, the MCLK runs at the same rate as the module clock, at
24.576 MHz.

The user manual suggests using different oversampling rates for different
sample rates, but that's not possible without a platform-specific machine
driver.

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
[wens@csie.org: Lowered oversampling rate to 128; expanded commit message]
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Tested-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>