staging; vt6656: device_init_registers Change vnt_cmd_card_int and vnt_rsp_card_int to off stack

Move structures to vnt_private and convert to pointers in
device_init_registers.

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