drm/i915: Drop fb reference on load_detect_pipe failure path

When intel_modeset_setup_plane_state() fails drop the local framebuffer
reference before jumping to the error, otherwise we leak the framebuffer.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Fixes: edde3617 ("drm/i915: Use atomic state to obtain load detection crtc, v3.")
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171207220025.22698-1-chris@chris-wilson.co.uk
(cherry picked from commit 3e72be17)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -9944,11 +9944,10 @@ int intel_get_load_detect_pipe(struct drm_connector *connector,
 	}
 
 	ret = intel_modeset_setup_plane_state(state, crtc, mode, fb, 0, 0);
+	drm_framebuffer_put(fb);
 	if (ret)
 		goto fail;
 
-	drm_framebuffer_put(fb);
-
 	ret = drm_atomic_set_mode_for_crtc(&crtc_state->base, mode);
 	if (ret)
 		goto fail;