drm/panel: visionox-rm69299: Fix clock frequency for SHIFT6mq

drm/panel: visionox-rm69299: Fix clock frequency for SHIFT6mq

Make the clock frequency match what the sdm845 downstream kernel
uses. Otherwise the panel stays black.

Fixes: 783334f366b18 ("drm/panel: visionox-rm69299: support the variant found in the SHIFT6mq")
Signed-off-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.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-v3-1-a7729911afb9@sigxcpu.org