ktest: For grub reboot, use run_ssh instead of run_command

The run_ssh handles the ssh variable $SSH_COMMAND, which was not
being used by the run_command in reboot_to function.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

tools/testing/ktest/ktest.pl

@@ -561,7 +561,7 @@ sub wait_for_input
 
 sub reboot_to {
     if ($reboot_type eq "grub") {
-	run_command "$ssh_exec '(echo \"savedefault --default=$grub_number --once\" | grub --batch; reboot)'";
+	run_ssh "'(echo \"savedefault --default=$grub_number --once\" | grub --batch; reboot)'";
 	return;
     }