fs: remove unused methods from File interface

internal/fs/interface.go

@@ -29,9 +29,7 @@ type File interface {
 	io.Reader
 	io.Closer
 
-	Fd() uintptr
 	Readdirnames(n int) ([]string, error)
-	Seek(int64, int) (int64, error)
 	Stat() (os.FileInfo, error)
 	Name() string
 }