Staging: w35und: usb_put_dev() is missing from wb35_disconnect()

The wb35_probe() function does usb_get_dev() so add a missing usb_put_dev() to
the wb35_disconnect() function. Also fix error handling paths in wb35_probe()
to call usb_put_dev() as well.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>