drm: don't unlock in the addfb error paths

We don't grab the modeset locks any more since

commit 468174f748603497e73dba9b5c6d1d9f71121486
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Dec 11 00:09:12 2012 +0100

    drm: push modeset_lock_all into ->fb_create driver callbacks

Reported-by: Ray Strode <rstrode@redhat.com>
Cc: Ray Strode <rstrode@redhat.com>
Cc: Dave Airlie <airlied@gmail.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_crtc.c

@@ -2326,7 +2326,6 @@ int drm_mode_addfb(struct drm_device *dev,
 	fb = dev->mode_config.funcs->fb_create(dev, file_priv, &r);
 	if (IS_ERR(fb)) {
 		DRM_DEBUG_KMS("could not create framebuffer\n");
-		drm_modeset_unlock_all(dev);
 		return PTR_ERR(fb);
 	}
 
@@ -2506,7 +2505,6 @@ int drm_mode_addfb2(struct drm_device *dev,
 	fb = dev->mode_config.funcs->fb_create(dev, file_priv, r);
 	if (IS_ERR(fb)) {
 		DRM_DEBUG_KMS("could not create framebuffer\n");
-		drm_modeset_unlock_all(dev);
 		return PTR_ERR(fb);
 	}