dt-bindings: mmc: cdns: Add AMD Pensando Elba SoC

AMD Pensando Elba ARM 64-bit SoC is integrated with this IP and
explicitly controls byte-lane enables.

Signed-off-by: Brad Larson <blarson@amd.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230410184526.15990-3-blarson@amd.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>