drm/msm/dpu: bail from _dpu_core_perf_crtc_update_bus if there are no ICC paths

Skip bandwidth aggregation and return early if there are no interconnect
paths defined for the DPU device.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/550195/
Link: https://lore.kernel.org/r/20230730010102.350713-3-dmitry.baryshkov@linaro.org