Kernel: Remove some duplicate forward declarations

Kernel/Forward.h

@@ -18,7 +18,6 @@ class DevFSInode;
 class DevFSPtsDirectoryInode;
 class DevFSRootDirectoryInode;
 class Device;
-class Device;
 class DiskCache;
 class DoubleBuffer;
 class File;
@@ -27,7 +26,6 @@ class FileSystem;
 class FutexQueue;
 class IPv4Socket;
 class Inode;
-class Inode;
 class InodeIdentifier;
 class InodeWatcher;
 class KBuffer;
@@ -73,7 +71,6 @@ class UDPSocket;
 class UserOrKernelBuffer;
 class VMObject;
 class VirtualFileSystem;
-class VirtualFileSystem;
 class WaitQueue;
 class WorkQueue;