[Issue]: MXFP6 support for A operand removed due to recent changes in #754

[amd-satre]

Problem Description

Recent changes in f5c50f4#diff-d76870d0abe4faede57451ca02ad6fdebc9db21d64b0dbb98f852d49906d3552L464 seems to have removed the MXFP6 support for A operand including the tests that checked for its correctness. One of the use cases for mxfp6 A operand can be seen in https://rocm.blogs.amd.com/artificial-intelligence/w4a6-quant-mm/README.html.

I can add my old changes back in kernels/mxfp4_preshuffle.py or we can have a separate kernel in kernels/mxfp6_preshuffle.py which will be very similar to the mxfp4 preshuffle kernel already present here. What do you think @coderfeli ?

CC @BowenBao

Operating System

Ubuntu 22.04

CPU

AMD Ryzen

GPU

AMD MI355X

ROCm Version

ROCm 7.2

ROCm Component

No response

Steps to Reproduce

No response

(Optional for Linux users) Output of /opt/rocm/bin/rocminfo --support

rocminfo --support output

Paste output here

Additional Information

No response