ARM: configs: at91: sama5: Add audio MIKROE PROTO board

Add this board as a module as it's useful for testing audio on multiple
AT91 boards.

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
[nicolas.ferre@microchip.com: adap to newer kernel]
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>