scsi: fdomain: Fix error return code in fdomain_probe()

If request_region() fails the return value is not set. Return -EBUSY on
error.

Link: https://lore.kernel.org/r/20210715032625.1395495-1-liwei391@huawei.com


Fixes: 8674a8aa ("scsi: fdomain: Add PCMCIA support")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>