arm64: defconfig: Enable the WM8524 codec driver

imx8mn-evk has a WM8524 codec.

Enable the WM8524 codec driver so that audio can be functional
on this board.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>