drm/amd/display: Fix uninitialized variables in DM

This fixes 11 UNINIT issues reported by Coverity.

Reviewed-by: Hersen Wu <[e-mail]>
Acked-by: Wayne Lin <[e-mail]>
Signed-off-by: Alex Hung <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

···
 static int dm_crtc_get_scanoutpos(struct amdgpu_device *adev, int crtc,
 				  u32 *vbl, u32 *position)
 {
-	u32 v_blank_start, v_blank_end, h_position, v_position;
+	u32 v_blank_start = 0, v_blank_end = 0, h_position = 0, v_position = 0;
 	struct amdgpu_crtc *acrtc = NULL;
 	struct dc *dc = adev->dm.dc;
 
···
  */
 static void dm_dmub_outbox1_low_irq(void *interrupt_params)
 {
-	struct dmub_notification notify;
+	struct dmub_notification notify = {0};
 	struct common_irq_params *irq_params = interrupt_params;
 	struct amdgpu_device *adev = irq_params->adev;
 	struct amdgpu_display_manager *dm = &adev->dm;
···
 	struct amdgpu_dm_connector *aconnector;
 	struct dm_connector_state *dm_conn_state;
 	int i, j, ret;
-	int vcpi, pbn_div, pbn, slot_num = 0;
+	int vcpi, pbn_div, pbn = 0, slot_num = 0;
 
 	for_each_new_connector_in_state(state, connector, new_con_state, i) {
 
···
 	struct dm_crtc_state *dm_old_crtc_state, *dm_new_crtc_state;
 	struct drm_dp_mst_topology_mgr *mgr;
 	struct drm_dp_mst_topology_state *mst_state;
-	struct dsc_mst_fairness_vars vars[MAX_PIPES];
+	struct dsc_mst_fairness_vars vars[MAX_PIPES] = {0};
 
 	trace_amdgpu_dm_atomic_check_begin(state);
 

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c

···
 				 size_t size, loff_t *pos)
 {
 	int r;
-	uint8_t data[36];
+	uint8_t data[36] = {0};
 	struct amdgpu_dm_connector *connector = file_inode(f)->i_private;
 	struct dm_crtc_state *acrtc_state;
 	uint32_t write_size = 36;
···
 {
 	struct amdgpu_dm_connector *connector = data;
 	struct dc_link *link = connector->dc_link;
-	u32 residency;
+	u32 residency = 0;
 
 	link->dc->link_srv->edp_get_psr_residency(link, &residency);