[llvm] [llvm-objdump][AMDGPU] Pass ELF ABIVersion through disassembler (PR #78907)

[Emma Pilkington via llvm-commits]

epilk wrote:

> > > Admittedly, its a bit ugly to pass the ABIVersion through onSymbolStart but I'm not sure what a better place for it would be.
> > 
> > 
> > I am indeed concerned about this. Can you place the version inside `AMDGPUDisassembler` instead?
> 
> +1. The ABIVersion should be constant for a given file, so it feels like it should be configured up front when configuring the disassembler (and therefore presumably stored somewhere inside the disassembler class).

Okay, I added a `virtual setABIVersion()` function to `MCDisassembler` in the update, so we can just store it in the disassembler. WDYT?

https://github.com/llvm/llvm-project/pull/78907