[llvm] [AArch64][llvm] (NFC) Refactor `sve_intx_dot` class and delete `sve2p1_two_way_dot_vv` (PR #160103)

[via llvm-commits]

Lukacma wrote:

Since we are already merging these 2, we might as well merge both multiclasses together as well. These are the same instructions, its just that intx_dot variants do 4 way sdot while two_way do 2 way sdot. I don't think there is a reason to have separate multiclass for that. 

https://github.com/llvm/llvm-project/pull/160103