drm/msm/dsi: add mode valid callback for dsi_mgr

Add a mode valid callback for dsi_mgr for checking mode being valid in
case of DSC. For DSC the height and width needs to be multiple of slice,
so we check that here

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Patchwork: https://patchwork.freedesktop.org/patch/480930/
Link: https://lore.kernel.org/r/20220406094031.1027376-13-vkoul@kernel.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>