ospf6d: move error logs out from behind debug flags

ospf6d: move error logs out from behind debug flags

The logging in ospf6 is very verbose.  If you turn on logging on a scaled
system you get too many logs.   The problem is that there are some errors
that occur that are hidden behind the debug flags, and to see these errors
we currently need to turn on the debug logging.  This change converts these
error logs to warnings and removes the debug flags.

Signed-off-by: Lynne Morrison <lynne@voltanet.io>