win: remove unnecessary initialization

There is no need to set req->fs.info.bufs to NULL and then
memset() the entire req->fs struct on the next line.

Refs: https://github.com/libuv/libuv/pull/1752#discussion_r169953154
PR-URL: https://github.com/libuv/libuv/pull/1762
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

src/win/fs.c

@@ -245,7 +245,6 @@ INLINE static void uv_fs_req_init(uv_loop_t* loop, uv_fs_t* req,
   req->ptr = NULL;
   req->path = NULL;
   req->cb = cb;
-  req->fs.info.bufs = NULL;
   memset(&req->fs, 0, sizeof(req->fs));
 }