drm/msm: dpu: Fix "WARNING: invalid free of devm_ allocated data"

[ Upstream commit ce25aa3ee6939d83979cccf7adc5737cba9a0cb7 ]

'dpu_enc' is a member of 'drm_enc'
And 'drm_enc' got allocated with devm_kzalloc in dpu_encoder_init.

This gives this error message:
./drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c:459:1-6:
 WARNING: invalid free of devm_ allocated data
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NRob Clark <robdclark@gmail.com>
Signed-off-by: NSean Paul <seanpaul@chromium.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>

drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c

@@ -503,8 +503,6 @@ static void dpu_encoder_destroy(struct drm_encoder *drm_enc)
 
 	drm_encoder_cleanup(drm_enc);
 	mutex_destroy(&dpu_enc->enc_lock);
-
-	kfree(dpu_enc);
 }
 
 void dpu_encoder_helper_split_config(