scsi: fnic: Simplify the return expression of vnic_wq_copy_alloc()

Simplify the return expression.

Link: https://lore.kernel.org/r/20200921082452.2592085-1-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>