Add hash for xilinx_v2025.2 version, so that example defconfigs can be
bumped to the latest version individually.
Since the license.txt changes with each release, move the hashes to version
specific directories instead of having a generic hash file.
xilinx_v2025.1 hash is moved to boot/xilinx-prebuilt/xilinx_v2025.1_update1
xilinx_v2025.2 hash is added to boot/xilinx-prebuilt/xilinx_v2025.2
Signed-off-by: Neal Frager <neal.frager@amd.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
