drm/msm: Use drm_mode_init() for on-stack modes

Initialize on-stack modes with drm_mode_init() to guarantee
no stack garbage in the list head, or that we aren't copying
over another mode's list head.

Based on the following cocci script, with manual fixups:
@decl@
identifier M;
expression E;
@@
- struct drm_display_mode M = E;
+ struct drm_display_mode M;

@@
identifier decl.M;
expression decl.E;
statement S, S1;
@@
struct drm_display_mode M;
... when != S
+ drm_mode_init(&M, &E);
+
S1

@@
expression decl.E;
@@
- &*E
+ E

Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221107192545.9896-4-ville.syrjala@linux.intel.com

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

@@ -237,12 +237,13 @@ static void dpu_encoder_phys_vid_setup_timing_engine(
 	unsigned long lock_flags;
 	struct dpu_hw_intf_cfg intf_cfg = { 0 };
 
+	drm_mode_init(&mode, &phys_enc->cached_mode);
+
 	if (!phys_enc->hw_ctl->ops.setup_intf_cfg) {
 		DPU_ERROR("invalid encoder %d\n", phys_enc != NULL);
 		return;
 	}
 
-	mode = phys_enc->cached_mode;
 	if (!phys_enc->hw_intf->ops.setup_timing_gen) {
 		DPU_ERROR("timing engine setup is not supported\n");
 		return;
@@ -634,7 +635,9 @@ static int dpu_encoder_phys_vid_get_frame_count(
 {
 	struct intf_status s = {0};
 	u32 fetch_start = 0;
-	struct drm_display_mode mode = phys_enc->cached_mode;
+	struct drm_display_mode mode;
+
+	drm_mode_init(&mode, &phys_enc->cached_mode);
 
 	if (!dpu_encoder_phys_vid_is_master(phys_enc))
 		return -EINVAL;