1. 原kernel/common目录下属于内核拓展组件，统一移入kernel/extend管理
2. Kconfig分层，各模块自己的配置放到自己目录下管理
3. 原platform下不属于平台的公共代码抽到kernel/common下，只留板级链接脚本和一些编译脚本指向device目录下触发平台相关的编译
4. 对外公共头文件统一抽到对外include路径
5. 废弃宏，头文件清理

close: #I48KI4
Signed-off-by: Narvinzzz <zhaotianyu9@huawei.com>
Change-Id: I0cf5ea81c92a8fa7b113da9cbdc8b7bc935f5aae

add BUILD.gn for all kernel modules
Signed-off-by: NCaoruihong <crh.cao@huawei.com>
Change-Id: I018446427bf64615f2596d47862b219659b58b34

1.remove redundant headfile in kernel, such as:
  compiler.h;debug.h;automount.h;inode.h;syslog.h;net.h;
2.split fs.h to file.h and driver.h
3.move vnode.h and path_cache.h to vfs/include
4.remove redundant interface and defines

close: #I3RTNR
Signed-off-by: Nmucor <mucorwang@gmail.com>

Change-Id: Ia6c1f6302407a707b3ec9b805f4c92d8a7970b86