drm/panel: Fix sphinx warning

Resolves the following warnings.
../drivers/gpu/drm/drm_panel.c:158: WARNING: Unexpected indentation.
../drivers/gpu/drm/drm_panel.c:159: WARNING: Block quote ends without a blank line; unexpected unindent.

Fixes: c59eb3cf ("drm/panel: Let of_drm_find_panel() return -ENODEV when the panel is disabled")
Cc: Boris Brezillon <boris.brezillon@bootlin.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180815203833.210143-1-sean@poorly.run