arm:goni:mmc: Add sd card detection and initialization.

This change allow to use sd card on Goni the same like mmc 0.
SD card is mmc dev 1, so it can be used like this: "fatls mmc 1:2".
SD card is inited even if eMMC initialization fails.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Minkyu Kang <mk7.kang@samsung.com>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>