qla4xxx: fix get_host_stats error propagation

qla4xxx was not always returning -EXYZ error codes when
qla4xxx_get_host_stats failed.

Signed-off-by: Mike Christie <[e-mail]>
Acked-by: Vikas Chaudhary <[e-mail]>
Reviewed-by: Hannes Reinecke <[e-mail]>
Signed-off-by: Christoph Hellwig <[e-mail]>

drivers/scsi/qla4xxx/ql4_os.c

···
 	if (!ql_iscsi_stats) {
 		ql4_printk(KERN_ERR, ha,
 			   "Unable to allocate memory for iscsi stats\n");
+		ret = -ENOMEM;
 		goto exit_host_stats;
 	}
 
···
 	if (ret != QLA_SUCCESS) {
 		ql4_printk(KERN_ERR, ha,
 			   "Unable to retrieve iscsi stats\n");
+		ret = -EIO;
 		goto exit_host_stats;
 	}
 	host_stats->mactx_frames = le64_to_cpu(ql_iscsi_stats->mac_tx_frames);