from unit directory).  It was also inconsistent with how it is
done since the parent commit:
  - Use vendor/model/specifier/version of the unit directory if possible,
  - fall back to one or more of vendor/model/specifier/version from the
    root directory depending on which ones are not present at the unit
    directory.

Fix this inconsistency by sharing the ROM scanner function between
modalias printer function and driver match function.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
R½Œ¢“xx