drm/msm/dpu: pull format flag definitions to mdp_format.h

In preparation to merger of formats databases, pull format flag
definitions to mdp_format.h header, so that they are visibile to both
dpu and mdp drivers.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/590425/
Link: https://lore.kernel.org/r/20240420-dpu-format-v2-4-9e93226cbffd@linaro.org