arch: microblaze: Fix spelling mistake "vesion" -> "version"

There is a spelling mistake in the comment. Fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210601103707.9701-1-colin.king@canonical.com
Signed-off-by: Michal Simek <michal.simek@xilinx.com>