libpci: hwdb: Remove ID_SUBSYSTEM and ID_GEN_SUBSYSTEM usage from pci_id_hwdb_lookup()

Currently used udev hwdb key "ID_MODEL_FROM_DATABASE" does not return
subsystem, but returns device name.

There is no udev hwdb key which returns subsystem or generic subsystem.
So remove ID_SUBSYSTEM and ID_GEN_SUBSYSTEM from pci_id_hwdb_lookup().

This change fixes issue that pci_id_hwdb_lookup() as subsystem name always
returned device name.