ecore-drm: Fix using uninitialized output value

Summary:
This revision fixed using of uninitialized value 'output'.
The usage can cause segmentation fault when it try to refer current_mode

@fix

Reviewers: devilhorns

Subscribers: cedric

Differential Revision: https://phab.enlightenment.org/D2448

src/lib/ecore_drm/ecore_drm_evdev.c

@@ -51,7 +51,7 @@ static void
 _device_output_set(Ecore_Drm_Evdev *edev)
 {
    Ecore_Drm_Input *input;
-   Ecore_Drm_Output *output;
+   Ecore_Drm_Output *output = NULL;
    const char *oname;
 
    if (!edev->seat) return;