staging: vt6656: removed usage of custom Ethernet header

Removed struct tagSEthernetHeader, replacing with struct ethhdr.
Not all checkpatch errors and warnings were removed.

Signed-off-by: Andres More <more.andres@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>