samd: audio_dma.c: Remove exceptions, just return early
samd: audio_dma.c: Remove exceptions, just return early

These were most useful debugging, but because this code can be reached
"outside of the VM", it's not actually permitted to throw exceptions here.

adafruit/circuitpython,adafruit/micropython,adafruit/circuitpython,adafruit/micropython,adafruit/circuitpython,adafruit/micropython,adafruit/circuitpython,adafruit/circuitpython,adafruit/micropython,adafruit/circuitpython,adafruit/micropython