import_ghidra - bitfields with enums don't always insert all enum items

[quietust]

When importing bitfields which contain enums, some of the enum entries get skipped - for example, tile_occupancy.building only imports the "Dynamic" entry, and tile_designation.traffic only imports the "Restricted" entry.

In some cases, it doesn't import any of them at all - for example, tile_designation skips from pile to smooth, skipping over dig.