BSD.usr.dist: remove obsolete usr/share/examples/drivers entry

In base 8f0a6a9aadb1f, usr/share/examples/drivers was cleaned up,
because it contained unmaintained scripts. The directory itself is
cleaned up by ObsoleteFiles.inc, but there was still an entry in
BSD.usr.dist that re-created the directory. Remove it.

Fixes: 8f0a6a9aadb1
MFC after: 3 days

(cherry picked from commit ac2f284258e4c6d5867aa6a411bd44df349fe416)