[iar]修复__LDREX 和 __STREX 报 declared implicitly 警告

related: https://github.com/RT-Thread/rt-thread/issues/7381

libcpu/arm/common/atomic_arm.c

@@ -12,6 +12,7 @@
 
 #if defined (__IAR_SYSTEMS_ICC__)     /* for IAR Compiler */
 #include <intrinsics.h>
+#include <iccarm_builtin.h>
 #endif
 /**
  \brief   LDR Exclusive (32 bit)
@@ -30,7 +31,7 @@
 #elif defined (__IAR_SYSTEMS_ICC__)     /* for IAR Compiler */
 _Pragma("inline=forced") __intrinsic rt_atomic_t __LDREXW(volatile rt_atomic_t *ptr)
 {
-    return __LDREX((unsigned int *)ptr);
+    return __iar_builtin_LDREX((volatile unsigned int *)ptr);
 }
 #elif defined (__GNUC__)                /* GNU GCC Compiler */
 __attribute__((always_inline))     static inline rt_atomic_t __LDREXW(volatile rt_atomic_t *addr)