tools/kvm_stat: fix error on interactive command 'g'

Fix an instance where print_all_gnames() is called without the mandatory
argument, resulting in a stack trace.
To reproduce, simply press 'g' in interactive mode.

Signed-off-by: Stefan Raspl <raspl@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/kvm/kvm_stat/kvm_stat

@@ -1195,7 +1195,7 @@ class Tui(object):
                                'This might limit the shown data to the trace '
                                'statistics.')
             self.screen.addstr(5, 0, msg)
-            self.print_all_gnames()
+            self.print_all_gnames(7)
             curses.echo()
             self.screen.addstr(3, 0, "Guest [ENTER or guest]: ")
             gname = self.screen.getstr()