drm/mcde: Reuse global DSI command defs

The MCDE DSI include file redefines some commands that
already exist in the common <video/mipi_display.h> header.

Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20191122072457.25619-1-linus.walleij@linaro.org