serial: There's no config CONSOLE

as there's no config CONSOLE (never has been as far as I can tell) and
noone has ever missed that piece of code, it should be safe to remove
it making the kernel a tiny bit less complex.

Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
Acked-by: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>