[llvm] [RISCV] Place mergeable small read only data into srodata section (PR #82214)

[Craig Topper via llvm-commits]

https://github.com/topperc approved this pull request.

This LGTM. @MaskRay does it look good to you? I think independent of the default small data limit we still need to fix this when there is a small data limit.

https://github.com/llvm/llvm-project/pull/82214