[RFE]：Add loongarch64 support in pmdk

[zhaixiaojuan]

Dear maintainer, I hope pmdk can consider adding support for loongarch64. I have submitted a PR and completed the verification locally: kilobyte/pmdk#11

The LoongArch architecture (LoongArch) is an Instruction Set Architecture (ISA) that has a RISC style.
Documentations:
ISA:
https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html
ABI:
https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html
More docs can be found at:
https://loongson.github.io/LoongArch-Documentation/README-EN.html