loongarch: Add support for ELF psABI v2.00 relocations

loongarch: Add support for ELF psABI v2.00 relocations

A new set of relocation types was added in the LoongArch ELF psABI v2.00
spec [1], [2] to replace the stack-based scheme in v1.00. Toolchain
support is available from binutils 2.40 and gcc 13 onwards.

This patch adds support for the new relocation types, that are simpler
to handle (in particular, stack operations are gone). Support for the
v1.00 relocs are kept for now, for compatibility with older toolchains.

[1] https://github.com/loongson/LoongArch-Documentation/pull/57
[2] https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html#_appendix_revision_history

Signed-off-by: Xiaotian Wu <wuxiaotian@loongson.cn>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>