Secondary MMC port on ORIGEN is connected to sdhci instance 0.
Support for secondary MMC port is extended by registering
sdhci instance 0.

Since sdhci instance 2 can contain a bootable media, sdhci
instance 0 is registered after instance 2.
Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
[kgene.kim@samsung.com: Added comments in registering sdhci]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>