microblaze: Remove ancient and fake microblaze version from cpu_ver table

We need to continue with next microblaze PVR version that's why
I have to remove that ancient version. These version strings not match
any versions. From Microblaze v5.00.a is possible to use this style.
I believe that none use ancients versions. If yes they will be just
labeled as unknown version.

Signed-off-by: Michal Simek <monstr@monstr.eu>