staging: vt6655: Replace MACvStart with VNSvOutPortB

Replace macro MACvStart with VNSvOutPortB and as it
was the only user, it can now be removed.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/d998305b4dec2827b0e13e49938e68a32517c487.1651957741.git.philipp.g.hortmann@gmail.com


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