drm/msm/dpu: remove extra drm_encoder_cleanup from the error path

The drmm handler will perform drm_encoder_cleanup() for us. Moreover if
we call drm_encoder_cleanup() manually, the drmm_encoder_alloc_release()
will spawn warnings at drivers/gpu/drm/drm_encoder.c:214. Drop these
extra drm_encoder_cleanup() calls.

Fixes: cd42c56d ("drm/msm/dpu: use drmm-managed allocation for dpu_encoder_virt")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reported-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Tested-by: Abhinav Kumar <quic_abhinavk@quicinc.com> #sm8250 CI
Patchwork: https://patchwork.freedesktop.org/patch/571562/
Link: https://lore.kernel.org/r/20231211145440.3647001-1-dmitry.baryshkov@linaro.org