ASoC: tlv320aic32x4: Add multi endpoint support

Support multiple endpoints on TLV320AIC32x4 codec port when
used in of_graph context.

This patch allows to share the codec port between two CPU DAIs.

Example:

Custom STM32MP157C board uses TLV320AIC32x4 audio codec. This codec
is connected to two serial audio interfaces, which are configured
either as rx or tx.

>From AsoC point of view the topolgy is the following:
// 2 CPU DAIs (SAI2A/B), 1 Codec (TLV320AIC32x4)
Playback: CPU-A-DAI(slave) -> (master)CODEC-DAI/port0
Record: CPU-B-DAI(slave) <- (master)CODEC-DAI/port0

In the DT two endpoints have to be associated to the codec port:
tlv320aic32x4_port: port {
tlv320aic32x4_tx_endpoint: endpoint@0 {
remote-endpoint = <&sai2a_endpoint>;
};
tlv320aic32x4_rx_endpoint: endpoint@1 {
remote-endpoint = <&sai2b_endpoint>;
};
};

However, when the audio graph card parses the codec nodes, it expects
to find DAI interface indexes matching the endpoints indexes.

The current patch forces the use of DAI id 0 for both endpoints,
which allows to share the codec DAI between the two CPU DAIs
for playback and capture streams respectively.

Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://patch.msgid.link/20240830231007.205707-1-marex@denx.de
Signed-off-by: Mark Brown <broonie@kernel.org>