drm/i915: set "ret" correctly on error paths

If "crtc" is NULL, then my static checker complains that "ret" isn't
initialized on that path.  It doesn't really cause a problem unless
"ret" is somehow set to -EDEADLK which is not likely.

Chris Wilson also noticed another error path where "ret" isn't set
correctly.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170414195425.GA8144@mwanda
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_display.c

@@ -9563,6 +9563,7 @@ int intel_get_load_detect_pipe(struct drm_connector *connector,
 	 */
 	if (!crtc) {
 		DRM_DEBUG_KMS("no pipe available for load-detect\n");
+		ret = -ENODEV;
 		goto fail;
 	}
 
@@ -9619,6 +9620,7 @@ found:
 		DRM_DEBUG_KMS("reusing fbdev for load-detection framebuffer\n");
 	if (IS_ERR(fb)) {
 		DRM_DEBUG_KMS("failed to allocate framebuffer for load-detection\n");
+		ret = PTR_ERR(fb);
 		goto fail;
 	}