dt-bindings: spi: zynqmp-qspi: Add power-domains and iommus properties

ZynqMP QSPI 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>
Link: https://lore.kernel.org/r/2afed7285061abbb5d9ad3b1e795b737dcff9693.1683102032.git.michal.simek@amd.com


Signed-off-by: Mark Brown <broonie@kernel.org>