[llvm] [AMDGPU][True16][MC] test update for v_mul_f16 in true16 (PR #119314)

[Joe Nash via llvm-commits]

https://github.com/Sisyph approved this pull request.

It looks like the test order is different in the t16_err and t16_promote that what is already here, which makes it harder to read the diff in those files. I checked this one, but for future patches maybe you can make the order match. In other files the order matches. LGTM

https://github.com/llvm/llvm-project/pull/119314