ARM: dts: iwg22d-sodimm: Enable LCD panel

ARM: dts: iwg22d-sodimm: Enable LCD panel

On the Generic SODIMM Development Platform there is an RGB LCD panel
directly connected to the DU output. It uses the TPU0 as backlight, one
GPIO pull-up configuration for power enable, R[2:7], G[2:7], B[2:7],
VSYNC, HSYNC, DU0_DISP and, DU0_CLK as inputs.

There is no encoder between the DU and the panel, therefore the default
connector driver is used.

The two variants of the iW-G22D should be mutually exclusive, therefore
this patch also disables the RGB LCD display when the HDMI extension board
is used.

Signed-off-by: Marian-Cristian Rotariu <marian-cristian.rotariu.rb@bp.renesas.com>
Link: https://lore.kernel.org/r/1583239490-8837-1-git-send-email-marian-cristian.rotariu.rb@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>