drm/panel: sharp-ls043t1le01: make use of prepare_prev_first

drm/panel: sharp-ls043t1le01: make use of prepare_prev_first

The DSI link must be powered up to let panel driver to talk to the panel
during prepare() callback execution. Set the prepare_prev_first flag to
guarantee this.

Fixes: 9e15123eca79 ("drm/msm/dsi: Stop unconditionally powering up DSI hosts at modeset")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20260323-panel-fix-v1-1-9f12b09161e8@oss.qualcomm.com