ARM: dts: imx6dl: remove 'lcdif' node

According to the "i.MX 6Solo/6DualLite Applications Processor
Reference Manual" Rev. 3, 09/2017 there is no LCDIF unit on the
i.MX6DL.

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>