tools/kvm_stat: removed unused function

Function available_fields() is not used in any place.
Signed-off-by: NStefan Raspl <raspl@linux.vnet.ibm.com>
Reviewed-by: NJanosch Frank <frankja@linux.vnet.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

tools/kvm/kvm_stat/kvm_stat

@@ -671,9 +671,6 @@ class TracepointProvider(object):
 
             self.group_leaders.append(group)
 
-    def available_fields(self):
-        return self.get_available_fields()
-
     @property
     def fields(self):
         return self._fields