drm/msm/dpu: Remove unused code

Eliminate the follow clang warning:

drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c:544:33: warning: variable
‘mode’ set but not used [-Wunused-but-set-variable].
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Fixes: 3177589c("drm/msm/dpu: encoder: drop unused mode_fixup callback")
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/487136/
Link: https://lore.kernel.org/r/20220524081413.37895-1-jiapeng.chong@linux.alibaba.comSigned-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>

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

@@ -541,7 +541,6 @@ static int dpu_encoder_virt_atomic_check(
 	struct dpu_encoder_virt *dpu_enc;
 	struct msm_drm_private *priv;
 	struct dpu_kms *dpu_kms;
-	const struct drm_display_mode *mode;
 	struct drm_display_mode *adj_mode;
 	struct msm_display_topology topology;
 	struct dpu_global_state *global_state;
@@ -559,7 +558,6 @@ static int dpu_encoder_virt_atomic_check(
 
 	priv = drm_enc->dev->dev_private;
 	dpu_kms = to_dpu_kms(priv->kms);
-	mode = &crtc_state->mode;
 	adj_mode = &crtc_state->adjusted_mode;
 	global_state = dpu_kms_get_global_state(crtc_state->state);
 	if (IS_ERR(global_state))