scsi: lpfc: fix block guard enablement on SLI3 adapters

Since f44ac12f1dcc, BG enablement is tracked with the LPFC_SLI3_BG_ENABLED
bit, which is set in lpfc_get_cfgparam before lpfc_sli_config_sli_port() is
called. The bit shouldn't be cleared before checking the feature.  Based on
problem analysis by David Bond.

Fixes: f44ac12f1dcc "scsi: lpfc: Memory allocation error during driver start-up on power8"
Tested-by: David Bond <dbond@suse.com>
Signed-off-by: Martin Wilck <mwilck@suse.com>
Cc: stable@vger.kernel.org # 4.17.x
Cc: stable@vger.kernel.org # 4.18.x
Cc: stable@vger.kernel.org # 4.19.x
Reviewed-by: Hannes Reinecke <hare@suse.com>
Acked-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_init.c

@@ -167,7 +167,11 @@ lpfc_config_port_prep(struct lpfc_hba *phba)
 		       sizeof(phba->wwpn));
 	}
 
-	phba->sli3_options = 0x0;
+	/*
+	 * Clear all option bits except LPFC_SLI3_BG_ENABLED,
+	 * which was already set in lpfc_get_cfgparam()
+	 */
+	phba->sli3_options &= (uint32_t)LPFC_SLI3_BG_ENABLED;
 
 	/* Setup and issue mailbox READ REV command */
 	lpfc_read_rev(phba, pmb);

drivers/scsi/lpfc/lpfc_sli.c

@@ -4965,7 +4965,6 @@ lpfc_sli_config_port(struct lpfc_hba *phba, int sli_mode)
 		phba->sli3_options &= ~(LPFC_SLI3_NPIV_ENABLED |
 					LPFC_SLI3_HBQ_ENABLED |
 					LPFC_SLI3_CRP_ENABLED |
-					LPFC_SLI3_BG_ENABLED |
 					LPFC_SLI3_DSS_ENABLED);
 		if (rc != MBX_SUCCESS) {
 			lpfc_printf_log(phba, KERN_ERR, LOG_INIT,