MLK-16302-1 drm/imx: dpu: plane: Free dpu_plane when bailout from dpu_plane_init

The dpu_plane is allocated with kzalloc() in dpu_plane_init().
In case, dpu_plane_init() fails after that allocation, the bailout path
should free the dpu_plane, otherwise, there will be memory leakage.

Signed-off-by: Liu Ying <victor.liu@nxp.com>