drm/msm/dpu: don't access mode pointer before it is set

Move the initializer for the mode variable to the declaration point to
remove unitialized variable access from the DEBUG_DPU macro. This fixes
the following warning:

drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c:250:37: note: initialize the variable 'mode' to silence this warning

Fixes: d7d0e73f ("drm/msm/dpu: introduce the dpu_encoder_phys_* for writeback")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/484346/
Link: https://lore.kernel.org/r/20220502082420.48409-1-dmitry.baryshkov@linaro.orgSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

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

@@ -247,7 +247,7 @@ static int dpu_encoder_phys_wb_atomic_check(
 		struct drm_connector_state *conn_state)
 {
 	struct drm_framebuffer *fb;
-	const struct drm_display_mode *mode;
+	const struct drm_display_mode *mode = &crtc_state->mode;
 
 	DPU_DEBUG("[atomic_check:%d, \"%s\",%d,%d]\n",
 			phys_enc->wb_idx, mode->name, mode->hdisplay, mode->vdisplay);
@@ -256,7 +256,6 @@ static int dpu_encoder_phys_wb_atomic_check(
 		return 0;
 
 	fb = conn_state->writeback_job->fb;
-	mode = &crtc_state->mode;
 
 	if (!conn_state || !conn_state->connector) {
 		DPU_ERROR("invalid connector state\n");