ARM: shmobile: marzen: add SDHI0 support

[horms@verge.net.au: moved defconfig portion into a separate patch]
[horms@verge.net.au: added "ARM: shmobile:" to title]
Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Tested-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms@verge.net.au>