drm/bridge: tc358775: Get bridge data lanes instead of the DSI host lanes

The current code assumes the data-lanes property is configured on the
DSI host side instead of the bridge side, and assumes DSI host endpoint 1.

Let's standardize on what the other bridge drivers are doing and parse the
data-lanes property for the bridge. Only if data-lanes property is not found,
let's be nice and also check the DSI host for old dtb in use and warn.

And as Dmitry pointed out, the lanes for the host and the bridge may be
different because the lanes may be swapped on the host side.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240225062008.33191-7-tony@atomide.com