[libcpu][cortex-m7] use hw atomic

libcpu/Kconfig

@@ -101,6 +101,7 @@ config ARCH_ARM_CORTEX_M7
     select ARCH_ARM_CORTEX_M
     select RT_USING_CPU_FFS
     select RT_USING_CACHE
+    select RT_USING_HW_ATOMIC
 
 config ARCH_ARM_CORTEX_M85
     bool