staging: vt6656: device_set_multi: covert mc_filter to u64

Convert mc_filter to u64, preform netdev_for_each_mc_addr
mask filtering.

In MACvWriteMultiAddr endian correct mc_filter and write
the entire multicast once.

Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>