Disable reduced precision reductions in FP16 and BF16 GEMMs

[voltjia]

pytest output:

============================= test session starts ==============================
platform linux -- Python 3.12.3, pytest-8.3.5, pluggy-1.5.0
rootdir: /home/voltjia/ntops
configfile: pyproject.toml
plugins: jaxtyping-0.3.2, anyio-4.9.0, cov-6.0.0
collected 6 items

tests/test_addmm.py ..                                                   [ 33%]
tests/test_bmm.py ..                                                     [ 66%]
tests/test_mm.py ..                                                      [100%]

======================== 6 passed in 388.29s (0:06:28) =========================