tipc: Eliminate alteration of publication key during name table purging

Removes code that alters the publication key of a name table entry
that is being forcibly purged from TIPC's name table after contact
with the publishing node has been lost.

Current TIPC ensures that all defunct names are purged before
re-establishing contact with a failed node.  There used to be a risk
that the publication might be accidentally deleted because it might be
re-added to the name table before the purge operation was completed.
But now there is no longer a need to ensure that the new key is different
than the old one.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>