dt-bindings: mmc: tegra: Reformat compatible string list

The list of compatible strings is somewhat difficult to read and extend.
Reformat it into a list to make it more easily extensible.

While at it, also remove the "plus one of the above" clause because it
isn't actually valid.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>