staging: vt6655: remove unnecessary null check

Remove null check for priv->tx0_bufs, because it can never be null at
this point.

Signed-off-by: Nam Cao <namcaov@gmail.com>
Link: https://lore.kernel.org/r/20220909100650.44609-1-namcaov@gmail.com


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