This case is hit for the kernel itself on riscv64, and did not used to
be checked. Since the code here can already handle missing Elf_Rel
and/or Elf_Rela just delete the check.
Reviewed by: jhb, imp
Fixes: 0299afdff1 ("kldxref: Make use of libelf to be a portable cross tool")
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D46517