drm/panel: himax-hx83102: restore MODE_LPM after sending disable cmds

drm/panel: himax-hx83102: restore MODE_LPM after sending disable cmds

When preparing the panel, it seems that it always expects commands to be
transferred in LP mode. However, the disable function removes the
MIPI_DSI_MODE_LPM flag, and no other function re-adds it.

As the unprepare function contains no DSI commands, re-adding the flag
just after disabling the panel should be safe. Add the code re-adding
the flag after the two commands for disabling the panel are sent.

This fixes screen unblanking (after blanking once) on
mt8188-geralt-ciri-sku1 device.

Cc: stable@vger.kernel.org # 6.11+
Fixes: 0ef94554dc40 ("drm/panel: himax-hx83102: Break out as separate driver")
Signed-off-by: Icenowy Zheng <zhengxingda@iscas.ac.cn>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20260425165751.1716569-1-zhengxingda@iscas.ac.cn