linux-imx

rbd: fix error return code in rbd_dev_device_setup()

Fix to return -ENOMEM from the workqueue alloc error handling
case instead of 0, as done elsewhere in this function.

Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>