arm64: zynqmp: Introduce u-boot options node with bootscr-address

Add u-boot options node with details about bootscr-address.
c&p description from dtschema/schemas/options/u-boot.yaml:

"Holds the full address of the boot script file. It helps in making
automated flow easier by fetching the 64bit address directly from DT.
Value should be automatically copied to the U-Boot 'scriptaddr' variable.
When it is defined, bootscr-ram-offset property should be ignored.
Actually only one of them should be present in the DT."

Address is generic for all zynqmp boards because all of them have DDR
starting from 0. Custom boards should revisit the location and aligned it
based on their needs.

Link: https://lore.kernel.org/r/4f5978d5a26fe0cd0cc6e54a97da1517bb925c01.1704728353.git.michal.simek@amd.com


Signed-off-by: Michal Simek <michal.simek@amd.com>