drm/msm/dpu: use drmm-managed allocation for dpu_plane

Change struct dpu_plane allocation to use drmm_universal_plane_alloc().
This removes the need to perform any actions on plane destruction.

Reviewed-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/570042/
Link: https://lore.kernel.org/r/20231201211845.1026967-10-dmitry.baryshkov@linaro.org