[llvm] [AMDGPU] Update MC tests for vflat instructions on GFX1250 (PR #151232)

[Changpeng Fang via llvm-commits]

changpeng wrote:

> > Apparently dasm tests do not match with asm ones, and quite a lot of instructions are missing. I am not sure whether this is intentional. Or we need to add missing dasm checks.
> 
> Yes, we need to add these, but in a separate PR and after the merge.

I think we are actually fine. Turned out far more instructions were added in dasm than asm in a previous commit. So they are balanced now after this patch. 

https://github.com/llvm/llvm-project/pull/151232