drm/panel: visionox-rm69299: Remove redundant assignments of panel fields

drm_panel_init() was made to initialize the fields in |struct drm_panel|.
There is no need to separately initialize them again.

Drop the separate assignments that are redundant. Also fix up any uses
of `ctx->panel.dev` to use `dev` directly.

Reviewed-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241204093942.1374693-1-wenst@chromium.org


Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>