arm64: zynqmp: Add ZynqMP SDHCI compatible string

Add the new compatible string for ZynqMP SD Host Controller for its use
in the Arasan SDHCI driver for some of the ZynqMP specific operations.
Add required properties for the same.

Signed-off-by: Manish Narani <manish.narani@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>