drm/amd/display: Initialize lt_settings on instantiation

[WHY]
lt_settings' pointers remain uninitialized but nonzero if display fails
to light up with no DPCD/EDID info populated, leading to a hang on access
Reviewed-by: NNicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: NAlan Liu <HaoPing.Liu@amd.com>
Signed-off-by: NMichael Strauss <michael.strauss@amd.com>
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link_dpia.c

@@ -960,7 +960,7 @@ enum link_training_result dc_link_dpia_perform_link_training(
 	bool skip_video_pattern)
 {
 	enum link_training_result result;
-	struct link_training_settings lt_settings;
+	struct link_training_settings lt_settings = {0};
 	uint8_t repeater_cnt = 0; /* Number of hops/repeaters in display path. */
 	int8_t repeater_id; /* Current hop. */