ARM: multi_v7_defconfig: Add rockchip audio support

As the rockchip SPDIF driver landed for 4.4 and the required clock
patches to make it work properly are scheduled for the 4.5 merge window
it seems time to support for audio device found on rockchip boards in
the defconfig as well.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>