ARM: mvebu: add audio support to Armada 370 DB

This commit adds the necessary Device Tree informations to enable
audio support on the Armada 370 DB platform. In details it:

 * Instantiates the CS42L51 audio codec on the I2C0 bus, and
   configures this bus with the appropriate pin-muxing configuration.

 * Enables the I2S audio controller, and configures it with the
   appropriate pin-muxing configuration.

 * Through hog pins, ensures that the other pins possibly used for I2S
   are muxed with another function than I2S.

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