dt-bindings: mmc: arasan,sdci: Add power-domains and iommus properties

ZynqMP SDHCI Arasan IP core has own power domain and also iommu ID that's
why describe optional power-domains and iommus properties.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/bf912d5f5e74b43903a84262565f564bfe0fed7e.1691047370.git.michal.simek@amd.com


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