Fix incorrect count of dma options for F3.
Value was hardcoded to 3, but the F3 has 4 ADCs.
Fix dmaPeripheralMapping for F3.
The dmaPeripheralMapping table was using index numbers and not device
numbers.
This meant all the dma mappings were out by one, eg.
```
```
ADC 1 is on DMA1, channel 1, but the output from dma ADC 2 list shows
the possibilities for ADC 1, not ADC 2 and shows no possibilities for
dma ADC 1 list
Ensure there are defaults for ADC4 on F3.
Always use 4 ADC instances for the ADC PG.
* PG should not be target dependant.
* Add a static assert which will fail if anything is changed.
Fix dmaopt in ADC PG, it should be a int8_t, not uint8_t
