dto: panel: Add "sel6_8_polarity" property
Add support of "sel6_8_polarity" node to the panel fragment of device tree. This property is handled by "panel-dt" driver to set the polarity of "sel6_8" gpio pin. The naming is inherited from corresponding XML files used by gfxml2dto.
Signed-off-by: Dmitry Petrov dmitry.petrov@rtsoft.de