trace: Remove redundant __GFP_NOWARN

Commit 16f5dfb ("gfp: include __GFP_NOWARN in GFP_NOWAIT")
made GFP_NOWAIT implicitly include __GFP_NOWARN.

Therefore, explicit __GFP_NOWARN combined with GFP_NOWAIT
(e.g., `GFP_NOWAIT | __GFP_NOWARN`) is now redundant. Let's clean
up these redundant flags across subsystems.

No functional changes.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250805023630.335719-1-rongqianfeng@vivo.com
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: qianfengrong

kernel/trace/trace_events_user.c

@@ -496,7 +496,7 @@ static bool user_event_enabler_queue_fault(struct user_event_mm *mm,
 {
 	struct user_event_enabler_fault *fault;
 
-	fault = kmem_cache_zalloc(fault_cache, GFP_NOWAIT | __GFP_NOWARN);
+	fault = kmem_cache_zalloc(fault_cache, GFP_NOWAIT);
 
 	if (!fault)
 		return false;