drivers/rpmsg: use NuttX atomic_t API instead of C11 atomics

Replace C11 atomic types and operations with NuttX native atomic
interfaces (atomic_t, atomic_set, atomic_fetch_and_acquire,
atomic_fetch_or_acquire) to avoid build failures on toolchains
that lack full C11 atomics support.

Signed-off-by: chenrun1 <chenrun1@xiaomi.com>
Signed-off-by: Bowen Wang <wangbowen6@xiaomi.com>

drivers/rpmsg/rpmsg.c

@@ -531,7 +531,7 @@ int rpmsg_register(FAR const char *path, FAR struct rpmsg_s *rpmsg,
   metal_list_init(&rpmsg->bind);
   nxrmutex_init(&rpmsg->lock);
   rpmsg->ops = ops;
-  atomic_store(&rpmsg->signals, RPMSG_SIGNAL_RUNNING);
+  atomic_set(&rpmsg->signals, RPMSG_SIGNAL_RUNNING);
 
   /* Add priv to list */
 
@@ -605,8 +605,8 @@ void rpmsg_modify_signals(FAR struct rpmsg_s *rpmsg,
   FAR struct metal_list *node;
   bool needlock;
 
-  atomic_fetch_and(&rpmsg->signals, ~clrflags);
-  atomic_fetch_or(&rpmsg->signals, setflags);
+  atomic_fetch_and_acquire(&rpmsg->signals, ~clrflags);
+  atomic_fetch_or_acquire(&rpmsg->signals, setflags);
 
   /* Send signal to Router Hub */
 

include/nuttx/rpmsg/rpmsg.h

@@ -67,7 +67,7 @@ struct rpmsg_s
 #ifdef CONFIG_RPMSG_TEST
   struct rpmsg_endpoint        test;
 #endif
-  atomic_int                   signals;
+  atomic_t                     signals;
 };
 
 struct rpmsg_timestamp_s