x86/tools: Remove special relocation handling for per-CPU variables

Due to the placement of per-CPU variables in a special, 0x0 based
disjoint memory segment in the ELF binary, the KASLR relocation tool
needed to perform special processing for references to such variables,
as they were not affected by KASLR displacement.

This meant that absolute references could be ignored, and RIP-relative
references had to be compensated for KASLR, by applying the same offset
but negated.

None of this is necessary any longer, so remove this handling from the
relocation host tool.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>