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

[Shilei Tian via llvm-commits]

shiltian wrote:

> > > 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?
> > 
> > 
> > Do we still want the sun style to work? I tried locally and the assembler can still recognize it.
> 
> Well we ideally wouldn't break existing asm people are relying on parsing

We can keep as it for now and probably add some checks when parsing Sun syntax after next release or so.

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