[NVPTX] Fix assumption of sm versioning (#188282)
The test case in #188118 assumes sm-90 is always available, leading to a
crash
```
# | ptxas fatal : SM version specified by .target is higher than default SM version assumed
```
This PR updates the test case to follow the check specified in
`llvm/test/CodeGen/NVPTX/cp-async-bulk-tensor-reduce.ll`,
namely `%if ptxas-sm_90 && ptxas-isa-7.8`
