ARM: dts: imx6sll-evk: enable SEIKO 43WVF1G lcdif panel

Enable SEIKO 43WVF1G lcdif panel for DRM driver,
add necessary properties according to SEIKO 43WVF1G
driver's requirement, such as "dvdd-supply", "avdd-supply"
and "backlight" etc..

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>