dt-bindings: mmc: Convert sdhci-pxa to json-schema

Convert the sdhci-pxa binding to DT schema format using json-schema.

At the same time, fix a couple of issues with the examples discovered by
the validation tool -- a semicolon instead of a comma and wrong node names.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Link: https://lore.kernel.org/r/20200521091356.2211020-2-lkundrak@v3.sk


Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>