[SCSI] mpt2sas: Introduced check for enclosure_handle to avoid crash

Kernel panic is seen because of enclosure_handle received from FW is zero.
Check is introduced before calling mpt2sas_config_get_enclosure_pg0.
Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/mpt2sas/mpt2sas_scsih.c

@@ -3663,12 +3663,11 @@ _scsih_add_device(struct MPT2SAS_ADAPTER *ioc, u16 handle, u8 phy_num, u8 is_pd)
 	sas_device->hidden_raid_component = is_pd;
 
 	/* get enclosure_logical_id */
-	if (!(mpt2sas_config_get_enclosure_pg0(ioc, &mpi_reply, &enclosure_pg0,
-	   MPI2_SAS_ENCLOS_PGAD_FORM_HANDLE,
-	   sas_device->enclosure_handle))) {
+	if (sas_device->enclosure_handle && !(mpt2sas_config_get_enclosure_pg0(
+	   ioc, &mpi_reply, &enclosure_pg0, MPI2_SAS_ENCLOS_PGAD_FORM_HANDLE,
+	   sas_device->enclosure_handle)))
 		sas_device->enclosure_logical_id =
 		    le64_to_cpu(enclosure_pg0.EnclosureLogicalID);
-	}
 
 	/* get device name */
 	sas_device->device_name = le64_to_cpu(sas_device_pg0.DeviceName);