staging: vt6655: Replace MACvReadISR with VNSvInPortD

Replace macro MACvReadISR with VNSvInPortD 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/ddd403a3f590cb81403197442b12c3986c98ba25.1651036713.git.philipp.g.hortmann@gmail.com


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