ide/atapi: Fix START STOP UNIT command completion

The command must be completed on all code paths. START STOP UNIT with
pwrcnd set should succeed without doing anything.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>

hw/ide/atapi.c

@@ -983,6 +983,7 @@ static void cmd_start_stop_unit(IDEState *s, uint8_t* buf)
 
     if (pwrcnd) {
         /* eject/load only happens for power condition == 0 */
+        ide_atapi_cmd_ok(s);
         return;
     }