scsi: lpfc: Use struct_size() helper

Prefer struct_size() over open-coded versions of idiom:

sizeof(struct-with-flex-array) + sizeof(typeof-flex-array-elements) * count

where count is the max number of items the flexible array is supposed to
contain.

Link: https://github.com/KSPP/linux/issues/160
Co-developed-by: Gustavo A. R. Silva <[e-mail]>
Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Co-developed-by: Kees Cook <[e-mail]>
Signed-off-by: Kees Cook <[e-mail]>
Signed-off-by: Justin Tee <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Kees Cook <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/lpfc/lpfc_ct.c

···
 		rap->obj[0].entity_id_len = vmid->vmid_len;
 		memcpy(rap->obj[0].entity_id, vmid->host_vmid, vmid->vmid_len);
 		size = RAPP_IDENT_OFFSET +
-			sizeof(struct lpfc_vmid_rapp_ident_list) +
-			sizeof(struct entity_id_object);
+		       struct_size(rap, obj, be32_to_cpu(rap->no_of_objects));
 		retry = 1;
 		break;
 
···
 		dap->obj[0].entity_id_len = vmid->vmid_len;
 		memcpy(dap->obj[0].entity_id, vmid->host_vmid, vmid->vmid_len);
 		size = DAPP_IDENT_OFFSET +
-			sizeof(struct lpfc_vmid_dapp_ident_list) +
-			sizeof(struct entity_id_object);
+		       struct_size(dap, obj, be32_to_cpu(dap->no_of_objects));
 		write_lock(&vport->vmid_lock);
 		vmid->flag &= ~LPFC_VMID_REGISTERED;
 		write_unlock(&vport->vmid_lock);