intel/tools: Fix aub_file initialization in intel_dump_gpu

intel/tools: Fix aub_file initialization in intel_dump_gpu

The `device` can be set earlier either by a command line or a by
intercepting an ioctl call to get the I915_PARAM_CHIPSET_ID done by
the application early.  In both cases `aub_file` and `devinfo` would
not be initialized.

Fix by splitting the conditions

- `device == 0`: use the FD to get both device and devinfo.
- Or `devinfo.gen == 0`: use `device` to initialize it.

And separatedly, initialize aub_file the first time it is needed.

Fixes: d594d2a0524 ("intel/tools: use device info initializer")
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>