[llvm] [AMDGPU][MC] Allow UC_VERSION_* constant reuse (PR #96461)

[Carl Ritson via llvm-commits]

perlfu wrote:

> Ideally we would just raise an error if it's redefined, not assert

I'm not against changing this to a `report_fatal_error` call, but it is a leaky check anyway.
It only covers the case that a symbol is initialized before a disassembler.
In most cases I would expect a disassembler to be initialized before symbols are parsed and redefinition happens.


https://github.com/llvm/llvm-project/pull/96461