tracing: Fix NULL vs IS_ERR() check in enable_instances()

The trace_array_create_systems() function returns error pointers, not
NULL.  Fix the check to match.

Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Fixes: e645535 ("tracing: Add option to use memmapped memory for trace boot instance")
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Dan Carpenter <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: Dan Carpenter

kernel/trace/trace.c

@@ -10507,7 +10507,7 @@ __init static void enable_instances(void)
 		}
 
 		tr = trace_array_create_systems(name, NULL, addr, size);
-		if (!tr) {
+		if (IS_ERR(tr)) {
 			pr_warn("Tracing: Failed to create instance buffer %s\n", curr_str);
 			continue;
 		}