[llvm] [NVPTX] disable combine-mad test for newer ptxas (PR #93919)

[Artem Belevich via llvm-commits]

Artem-B wrote:

> @Artem-B, this addresses your request from [#93628 (comment)](https://github.com/llvm/llvm-project/pull/93628#discussion_r1621453827). Can you clarify what version of ptxas you're using and what error you're seeing?

The error:
```
[  4] ; RUN: %if ptxas %{ llc < %s -mtriple=nvptx -mcpu=sm_20 -O1 | %ptxas-verify %} [FAIL]
 llc < /build/work/ea8b3a3717bb294ac025e537a8aabcc8890c/google3/runfiles/google3/third_party/llvm/llvm-project/llvm/test/CodeGen/NVPTX/combine-mad.ll -mtriple=nvptx -mcpu=sm_20 -O1 | /build/work/ea8b3a3717bb294ac025e537a8aabcc8890c/google3/runfiles/google3/third_party/gpus/cuda_12_0/bin/ptxas -arch=sm_60 -c -o /dev/null - 
ptxas warning :  64 Bit host architecture (--machine) being used mismatches with .address_size of 32 bits
ptxas fatal   :  32-Bit compilation is no longer supported
Command failed: exit status 255
```

https://github.com/llvm/llvm-project/pull/93919