ui/console: move console compatibility check to dcl_display_console()

ui/console: move console compatibility check to dcl_display_console()

The current checks are done at registration time only. However, if a DCL
has no specific console specified, it may be switched dynamically with
console_select() later on.

Let's move the checks when displaychangelistener_display_console() is
called, which includes registration time and remains fatal if the
specified console is incompatible.

Note: we may want to display the compatibility error to the DCL, this is
left for a future improvement.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>