stm32/i2s: Initial implementation of I2S peripheral

[bergzand]

Contribution description

This is a (very) initial implementation of the stm32 SPI peripheral running in I2S mode.

Testing procedure

No test application yet.

At least the stm32f4discovery board has a I2S peripheral via the SPI3 interface.

Issues/PRs references

Implementation based on #15131

[Teufelchen1]

Hello! :lady_beetle:

what is the status on this?

[bergzand]

what is the status on this?

Waiting for feedback on #15131