[mlir][gpu] Fix option parsing in `TargetOptions`

`TargetOptions` includes a field for passing additional command line options to
the GPU compilation process. This field is typically used during the 'gpu-module-to-binary`
pass:
```
--gpu-module-to-binary=opts="-v -c"
```

The problem is that `tokenizeCmdOptions` receives the quoted string, which produces an
incorrect tokenization for `"-v -c"`. This patch removes quotes, fixing this issue.

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D159434