scsi: lpfc: Fix BlockGuard enablement on FCoE adapters

The driver is allowing the user to change lpfc_enable_bg while loading the
driver against a FCoE adapter. This is not supported.

No check is made for the adapter type when applying the blockguard
enablement value.

Fix by verifying the adapter type before setting the enablement flag.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>