This patch removes the need for secretXMLPath. Instead save 'path' during
loadSecret as 'configFile'. The secretXMLPath is nothing more than an
open coded virFileBuildPath.  All that code did was concantenate the
driver->configDir, the UUID of the secret, and the ".xml" suffix to form
the configFile name which we now will generate and save instead.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>