[lld] [lld][Mips] Remove signed range check for R_MICROMIPS_26_S1 (PR #228880)

[Fangrui Song via llvm-commits]

MaskRay wrote:

The merged commit looks good, and I like the `mips-micro-*` following existing convention. I won't have much bandwidth to follow MIPS updates closely, but please tag me before merging future changes so I can double-check for style consistency.

https://github.com/llvm/llvm-project/pull/228880