tty: Add support of /dev/console

/dev/console is a system console which provided
by the system with major 5 and minor 1. It's usually
configured on system startup with console= option
and underlied driver is resposible to deliver messages
to the console user.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>