[llvm] AMDGPU: Remove the dot4 test in insert-delay-alu-wmma-xdl.mir, NFC (PR #149375)

[Changpeng Fang via llvm-commits]

changpeng wrote:

> Honestly I don't follow…
This is related to PR:  https://github.com/llvm/llvm-project/pull/149208, specifically the following piece of code:

// WMMA XDL ops are treated the same as TRANS.
    if (AMDGPU::isGFX1250(*ST) && SII->isXDLWMMA(MI))
      return TRANS;

The DOT instruction test is not relevant. But this test is causing a failure in one of the downstream branch.
The reason the DOT instruction check was there is because people once though DOT can also be treated as a TRAN, 
and later confirmed not. Thus that is in an intermediate state. 

https://github.com/llvm/llvm-project/pull/149375