lkpifill_pci_dev() uses a sequene of kobject_init/set_name/add.
The problem is that kobject_add could fail.

Move the entire logic to the beginning of the function,
switch to kobject_init_and_add() and check the return code.
Make lkpifill_pci_dev() return the error and deal in the callers
with a possible error accordingly.

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MFC after: 3 days