[llvm] [AMDGPU][MC] Use normal ELF syntax for section switching (PR #77267)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

Does the assembler still recognize the sun syntax? Can you add a test for what happens if you try reading old asm with the sun name?

https://github.com/llvm/llvm-project/pull/77267