xilinx: fru: Replace spaces with \0 in detected revision

Also fix board revision field where spaces are used instead of \0.
The same change was done for board name by commit 530560b6 ("xilinx:
fru: Replace spaces with \0 in detected name").

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/e069e5134e57899e859786ad8ba48721df6df752.1653911444.git.michal.simek@amd.com