ARM: dt: tegra cardhu: fix typo in SDHCI node name

commit 1dfebb426cfd16e2080f8c95e00ca2462f2325d4 upstream.

Cardhu's eMMC controller is on sdhci@78000600, not sdhci@78000400.
Fix the typo. This roughly doubles the IO performance, since the
support-8bit property actually takes effect.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>