[LoongArch] Define the LAELF v20230519 relocs

The LoongArch ELF psABI document has changed location and versioning
scheme; this revision is v2.10 in the old scheme. Notably this revision
brings initial capability of linker relaxation to LoongArch.

Reviewed By: SixWeining, MaskRay

Differential Revision: https://reviews.llvm.org/D152184