tty: vt: use sizeof(*variable) where possible

Instead of sizeof(type), use sizeof(*variable) which is preferred. We
are going to remove the unicode's char32_t typedef, so this makes the
switch easier.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230112080136.4929-4-jirislaby@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>