vz: remove error logging from prlsdkUUIDParse
    
    As far as not every call of prlsdkUUIDParse assume correct UUID
    supplied, there is no use to complain about wrong format in it.
    Otherwise our log is flooded with false error messages.
    For instance, calling prlsdkUUIDParse from prlsdkEventsHandler
    works as a filter and in case of uuid absence for event issuer,
    we simply know that we shouldn't continue further processing.
    Instead of error logging for all calls we should explicitly take
    into accaunt where it is called from.
    
    Signed-off-by: Maxim Nestratov <mnestratov@virtuozzo.com>
    Signed-off-by: Michal Privoznik <mprivozn@redhat.com>