STM32: L4xx: SAI should not be enabled for all MCUs

### Describe the bug

- Platform:
 STM32L4xx Series
- Issue:
 At the moment SAI is enabledin all STM32L4xx MCUs. However, not all STM32L4xx MCUs support SAI.
- Regression:
 No

### Regression

- [ ] This is a regression.

### Steps to reproduce

_No response_

### Relevant log output

_No response_

### Impact

Not sure

### Environment

_No response_

### Additional Context

_No response_