drm/msm/dpu: drop DPU_HW_SUBBLK_INFO macro

As the subblock info is now mostly gone, inline and drop the macro
DPU_HW_SUBBLK_INFO.

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/570106/
Link: https://lore.kernel.org/r/20231201234234.2065610-8-dmitry.baryshkov@linaro.org