drm: Include the header with the prototype for drm_get_panel_orientation_quirk()

drm: Include the header with the prototype for drm_get_panel_orientation_quirk()

sparse complains:
drivers/gpu/drm/drm_panel_orientation_quirks.c:133:5: warning: symbol 'drm_get_panel_orientation_quirk' was not declared. Should it be static?

Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180226142423.26439-1-ville.syrjala@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>