drm/msm/dpu: stop embedding dpu_hw_blk into dpu_hw_intf

Now as dpu_hw_intf is not hanled by dpu_rm_get_assigned_resources, there
is no point in embedding the (empty) struct dpu_hw_blk into dpu_hw_intf
(and using typecasts between dpu_hw_blk and dpu_hw_intf). Drop it and
use dpu_hw_intf directly.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Link: https://lore.kernel.org/r/20220121210618.3482550-5-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>