scsi: lpfc: Fix some error codes in debugfs

If copy_from_user() or kstrtoull() fail then the correct behavior is to
return a negative error code.

Link: https://lore.kernel.org/r/YEsbU/UxYypVrC7/@mwanda
Fixes: f9bb2da1

 ("[SCSI] lpfc 8.3.27: T10 additions for SLI4")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>