drm/bridge: tc358775: remove unused drm_panel.h include

The file uses the panel_bridge APIs from drm_bridge.h, but no drm_panel
APIs from drm_panel.h.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250206-drm-cleanups-v1-6-93df60faa756@bootlin.com