ARM: mvebu: enable audio options in mvebu_defconfig

Since at least the Armada 370 SoC has audio support, it makes sense to
enable the corresponding kernel configuration options in
mvebu_defconfig.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>