fix: 修改某些平台保存bbox日志失败的问题

1、在日志写如完成之后执行fsync确保落盘。

Close #I41UTP
Signed-off-by: Nqidechun <qidechun@huawei.com>

kernel/common/blackbox/los_blackbox_common.c

@@ -78,6 +78,7 @@ int FullWriteFile(const char *filePath, const char *buf, size_t bufSize, int isA
         totalToWrite -= writeThisTime;
         totalWrite += writeThisTime;
     }
+    (void)fsync(fd);
     (void)close(fd);
 
     return (totalWrite == (int)bufSize) ? 0 : -1;
@@ -124,4 +125,4 @@ bool IsLogPartReady(void)
 {
     return TRUE;
 }
-#endif
\ No newline at end of file
+#endif