arm64: zynqmp: Add u-boot command to boot into recovery image

arm64: zynqmp: Add u-boot command to boot into recovery image

To boot into the firmware recovery tool, the user currently
needs to press a button on the board while powering the
system up. To simplify this process, a U-Boot command
was added to allow booting directly into the recovery tool.

For example:
ZynqMP> zynqmp reboot <multiboot offset in hex>

Co-develop-by: Prasad Kummari <prasad.kummari@amd.com>
Signed-off-by: Prasad Kummari <prasad.kummari@amd.com>
Co-develop-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/20240827115529.2931334-1-prasad.kummari@amd.com