drm/panel: visionox-rm69299: Don't clear all mode flags

drm/panel: visionox-rm69299: Don't clear all mode flags

[ Upstream commit 39144b611e9cd4f5814f4098c891b545dd70c536 ]

Don't clear all mode flags. We only want to maek sure we use HS mode
during unprepare.

Fixes: c7f66d32dd431 ("drm/panel: add support for rm69299 visionox panel")
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250910-shift6mq-panel-v3-2-a7729911afb9@sigxcpu.org
Signed-off-by: Sasha Levin <sashal@kernel.org>