boards: xtensa: Add board definition for Audio DSP on Up Squared

Create a board definition for the Audio DSP found on the Up Squared
board.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
15 files changed