drm/bridge: ti-sn65dsi86: Rename the main driver data structure

In preparation for splitting this driver into sub-drivers, let's
rename the main data structure so it's clear that it's holding data
for the whole device and not just the MIPI-eDP bridge part.

This is a no-op change.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210423095743.v5.2.Ib03e88304a9ea1c503f1b9567be5cbf8b7c5761c@changeid