zd1201: do not use stack as URB transfer_buffer

Patch fixes zd1201 not to use stack as URB transfer_buffer. URB buffers need
to be DMA-able, which stack is not.

Patch is only compile tested.

Cc: stable@vger.kernel.org
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>