util: consolidate on one free callback for hash data

This previous commit introduced a simpler free callback for
hash data with only 1 arg, the value to free:

commit 49288fac965f0ee23db45d83ae4ef3a9a71dafd0
Author: Peter Krempa <pkrempa@redhat.com>
Date: Wed Oct 9 15:26:37 2019 +0200

util: hash: Add possibility to use simpler data free function in virHash

It missed two functions in the hash table code which need
to call the alternate data free function, virHashRemoveEntry
and virHashRemoveSet.

After the previous patch though, there is no code that
makes functional use of the 2nd key arg in the data
free function. There is merely one log message that can
be dropped.

We can thus purge the current virHashDataFree callback
entirely, and rename virHashDataFreeSimple to replace
it.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>