ui/vc: Do not inherit the size of active console

ui/vc: Do not inherit the size of active console

A chardev-vc used to inherit the size of a graphic console when its
size not explicitly specified, but it often did not make sense. If a
chardev-vc is instantiated during the startup, the active graphic
console has no content at the time, so it will have the size of graphic
console placeholder, which contains no useful information. It's better
to have the standard size of text console instead.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20240319-console-v2-1-3fd6feef321a@daynix.com>