ARM: tegra: harmony: register sdhci devices

Add the 3 sdhci devices that are available on Harmony as
platform devices. Two go to slots (one 4-lane, one 8-lane),
and one goes to onboard wifi.

Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Colin Cross <ccross@android.com>