orinoco_usb: return error in ezusb_probe when alloc_orinocodev fails

The current code exits after alloc_orinocodev, but fails to change the
return value to something that indicates the failure.  This patch
changes the return value to -ENOMEM.

https://bugzilla.kernel.org/show_bug.cgi?id=106181



Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>