arm64: defconfig: Enable additional sound drivers on i.MX8M Mini

The i.MX8M Mini has micfil and SPDIF support but the drivers
are not being loaded.

This patch updates the defconfig to add support for these drivers.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>