dts: renesas: smartbond: Add support for the display driver class.

Define a single node that reflects the LCDC IP. Instead of defining
the same IP block twice with different compatibles (mipi dbi, display)
we define a single node for the default display interface and
other interfaces like the MIPI DBI should override the compatible entry
with the appropriate one within its DTS overlay file.

Signed-off-by: Ioannis Karachalios <ioannis.karachalios.px@renesas.com>