dt-bindings: memory-controller: Update example for Tegra124 EMC

The example in the Tegra124 EMC device tree binding looks like an old
version that doesn't contain all the required fields. Update it with a
version from the current DTS files to fix the make dt_binding_check
target.

Reported-by: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
[robh: also fix missing '#reset-cells']
Signed-off-by: Rob Herring <robh@kernel.org>