scsi: qedf: Fix error return code in __qedf_probe()

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

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Chad Dupuis <chad.dupuis@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>