scsi: qla2xxx: Check kzalloc() return value

scsi: qla2xxx: Check kzalloc() return value

Instead of crashing if kzalloc() fails, make qla2x00_get_host_stats()
return -ENOMEM.

Link: https://lore.kernel.org/r/20210320232359.941-8-bvanassche@acm.org
Fixes: b088b8c8bd09 ("scsi: qla2xxx: Implementation to get and manage host, target stats and initiator port")
Cc: Himanshu Madhani <himanshu.madhani@oracle.com>
Cc: Saurav Kashyap <skashyap@marvell.com>
Cc: Nilesh Javali <njavali@marvell.com>
Cc: Quinn Tran <qutran@marvell.com>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Daniel Wagner <dwagner@suse.de>
Cc: Lee Duncan <lduncan@suse.com>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Acked-by: Saurav Kashyap <skashyap@marvell.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>