make path matching in devfs rules consistent and sane (and safer)

Before this change path matching had the following features:

• for device nodes the patterns were matched against full path
• in the above case '/' in a path could be matched by a wildcard
• for directories and links only the last component was matched

So, for example, a pattern like 're*' could match the following entries:

• re0 device
• responder/u0 device
• zvol/recpool directory

Although it was possible to work around this behavior (once it was spotted
and understood), it was very confusing and contrary to documentation.

Now we always match a full path for all types of devfs entries (devices,
directories, links) and a '/' has to be matched explicitly.
This behavior follows the shell globbing rules.

This change is originally developed by Jaakko Heinonen.
Many thanks!

PR: kern/122838
Submitted by: jh
MFC after: 4 weeks