dt-bindings: display: bridge: waveshare,dsi2dpi: Document 1..4 DSI lane support

dt-bindings: display: bridge: waveshare,dsi2dpi: Document 1..4 DSI lane support

Describe 1..4 DSI lanes as supported. Internally, this bridge is
an ChipOne ICN6211 which loads its register configuration from a
dedicated storage and its I2C does not seem to be accessible. The
ICN6211 supports up to 4 DSI lanes, so this is a hard limit for
this bridge. The lane configuration is preconfigured in the bridge
for each of the WaveShare panels.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20260115024004.660986-1-marek.vasut+renesas@mailbox.org
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>