drm/amd/display: Fix dmub trace event not update issue

[Why & How]
Reference to read pointer which is incorrect.
Change to reference to write pointer.
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NYongqiang Sun <yongqiang.sun@amd.com>
Reviewed-by: NTony Cheng <Tony.Cheng@amd.com>
Acked-by: NEryk Brol <eryk.brol@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c

@@ -722,7 +722,7 @@ enum dmub_status dmub_srv_cmd_with_reply_data(struct dmub_srv *dmub,
 static inline void dmub_rb_out_trace_buffer_front(struct dmub_rb *rb,
 				 void *entry)
 {
-	const uint64_t *src = (const uint64_t *)(rb->base_address) + rb->rptr / sizeof(uint64_t);
+	const uint64_t *src = (const uint64_t *)(rb->base_address) + rb->wrpt / sizeof(uint64_t);
 	uint64_t *dst = (uint64_t *)entry;
 	uint8_t i;