Fix enumeration leafref lookup
Leafref lookup for straight uses of enumeration typedefs seems
to be failing. The code in question seems to rely on weird assumptions,
hence this patch places a FIXME and turns an alternative branch
into a fallback if the weird code fails to find a definition.
This also activates ietf-hardware models.
JIRA: MDSAL-352
Change-Id: I6d342c7418c1538ee928f85b33f8f58da8aca5c6
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit
6e6a3ea2c895e31da3a74da26fb0462095594cb1)