fusionsound: Fix crash in dummy driver when no driver is set.
fusionsound: Fix crash in dummy driver when no driver is set.

Distrotech/DirectFB,sklnet/DirectFB,deniskropp/DirectFB,sklnet/DirectFB,dfbdok/DirectFB1,djbclark/directfb-core-DirectFB,Distrotech/DirectFB,kaostao/directfb,lancebaiyouview/DirectFB,djbclark/directfb-core-DirectFB,djbclark/directfb-core-DirectFB,kevleyski/DirectFB-1,DirectFB/directfb,kevleyski/directfb,mtsekm/test,lancebaiyouview/DirectFB,deniskropp/DirectFB,kevleyski/directfb,dfbdok/DirectFB1,deniskropp/DirectFB,djbclark/directfb-core-DirectFB,sklnet/DirectFB,kaostao/directfb,mtsekm/test,lancebaiyouview/DirectFB,kevleyski/directfb,kevleyski/DirectFB-1,mtsekm/test,jcdubois/DirectFB,sklnet/DirectFB,dfbdok/DirectFB1,lancebaiyouview/DirectFB,DirectFB/directfb,jcdubois/DirectFB,kevleyski/DirectFB-1,deniskropp/DirectFB,jcdubois/DirectFB,kaostao/directfb,Distrotech/DirectFB,kevleyski/DirectFB-1,DirectFB/directfb,kevleyski/directfb