staging: vt6655: Replace MACvTransmitAC0 with function vt6655_mac_dma_ctl

Convert macro MACvTransmitAC0 to existing static function. This saves
codelines and multiline macros are not liked by kernel community.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/013abd177d9ac129c034776f10cdf823fd87d781.1659080988.git.philipp.g.hortmann@gmail.com


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