drm/msm/dpu: Set possible clones for all encoders

Set writeback encoders as possible clones for DSI encoders and vice
versa.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/637498/
Link: https://lore.kernel.org/r/20250214-concurrent-wb-v6-14-a44c293cf422@quicinc.com


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