Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

include/scsi/scsi_host.h

@@ -46,7 +46,7 @@ struct blk_queue_tags;
 enum {
 	SCSI_QDEPTH_DEFAULT,	/* default requested change, e.g. from sysfs */
 	SCSI_QDEPTH_QFULL,	/* scsi-ml requested due to queue full */
-	SCSI_QDEPTH_RAMP_UP,	/* scsi-ml requested due to threshhold event */
+	SCSI_QDEPTH_RAMP_UP,	/* scsi-ml requested due to threshold event */
 };
 
 struct scsi_host_template {