Fixing our kernel build

Hello everyone,

it has always been a little messy when it comes to the KVER variable. Depending on when it was used, usually things were appended to it to get the *actual* kernel release. Chaotic.

Since we now only build one kernel (and probably will be for the near future) a lot of this is no longer needed and so I consolidated the use of this variable.

Since the kernel release was put together in an inconsistent way, it was impossible to build any release candidate kernels because they later got installed in various places, but not where they were supposed to be.

This is now no longer a problem since there is only one easy way to find out which kernel we are building for.

This patchset does not introduce any functional changes.

Best, -Michael