drm/mcde: dsi: Make video mode errors more verbose

Triggering an error conditions in DSI video mode only results in
a very generic "some video mode error status" error message
at the moment.

Make this more clear by adding separate error messages for each bit.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20191106165835.2863-4-stephan@gerhold.net