ARM: shmobile: lager: add sound support

This patch adds sound support for Lager board.
But, it is using PIO transfer at this point.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
[horms+renesas@verge.net.au: resolved conflicts]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>