[llvm] [RISCV, GISel] Unconditionally use MO_PLT for calls (PR #72355)

[Michael Maitland via llvm-commits]

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

LGTM. I think the SDAG equivalent and removal of RISCVII::MO_CALL can be done in a different patch, and shouldn't hold this patch up.

https://github.com/llvm/llvm-project/pull/72355