[LoongArch] Add earlyclobber of destination register to atomic instructions

If the AM* atomic memory access instruction has the same register number as
rd and rj, the execution will trigger an Instruction Non-defined Exception.
If the AM* atomic memory access instruction has the same register number as
rd and rk, the execution result is uncertain.

Reference: https://github.com/loongson/LoongArch-Documentation

Differential Revision: https://reviews.llvm.org/D135641