drm/meson: use default case for unsupported DSI pixel formats

drm/meson: use default case for unsupported DSI pixel formats

Use default instead of listing unsupported formats explicitly, so the
switch statements don't need updating each time a new pixel format is
added.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
Patchwork: https://patchwork.freedesktop.org/patch/713715/
Link: https://lore.kernel.org/r/20260324-dsi-rgb101010-support-v5-2-ff6afc904115@pm.me
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>