[Bug]: ProcessingRate is advertised but unimplemented

### Which component impacted?

_No response_

### Is it regression? Good in old configuration?

None

### What happened?

This issue is LLM generated

This driver exposes VA_PROCESSING_RATE_ENCODE but doesn't implement QueryProcessingRate

capstable_data_av1_encode_xe3_lpm_r0_specific.h:81
```
{VAConfigAttribProcessingRate, VA_PROCESSING_RATE_ENCODE},
```

media_libva_interface_next.cpp:5340
```
VAStatus MediaLibvaInterfaceNext::QueryProcessingRate(
VADriverContextP ctx,
VAConfigID configId,
VAProcessingRateParameter *procBuf,
uint32_t *processingRate)
{
DDI_FUNC_ENTER;
return VA_STATUS_ERROR_UNIMPLEMENTED;
}
```

### What's the usage scenario when you are seeing the problem?

Transcode for media delivery

### What impacted?

_No response_

### Debug Information

_No response_

### Do you want to contribute a patch to fix the issue?

None