staging: vt6656: use off stack for in buffer USB transfers.

commit 05c0cf88 upstream.

Since 4.9 mandated USB buffers to be heap allocated. This causes
the driver to fail.

Create buffer for USB transfers.

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