Kernel/Devices: Remove required_mode and device_name methods

These methods are no longer needed because SystemServer is able to
populate the DevFS on its own.

Device absolute_path no longer assume a path to the /dev location,
because it really should not assume any path to a Device node.

Because StorageManagement still needs to know the storage name, we
declare a virtual method only for StorageDevices to override, but this
technique should really be removed later on.

Kernel/TTY/VirtualConsole.cpp

@@ -359,11 +359,6 @@ void VirtualConsole::set_cursor_style(VT::CursorStyle)
     // Do nothing
 }
 
-String VirtualConsole::device_name() const
-{
-    return String::formatted("tty{}", minor());
-}
-
 void VirtualConsole::echo(u8 ch)
 {
     m_console_impl.on_input(ch);