zd1211rw: fix storage endpoint lookup

commit 2d68bb2687abb747558b933e80845ff31570a49c upstream.

Make sure to use the current alternate setting when verifying the
storage interface descriptors to avoid submitting an URB to an invalid
endpoint.

Failing to do so could cause the driver to misbehave or trigger a WARN()
in usb_submit_urb() that kernels with panic_on_warn set would choke on.

Fixes: a1030e92 ("[PATCH] zd1211rw: Convert installer CDROM device into WLAN device")
Cc: stable <stable@vger.kernel.org>     # 2.6.19
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>