Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index aefadc6..95019c7 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -567,7 +567,7 @@
 	.revalidate_disk = sr_block_revalidate_disk,
 	/* 
 	 * No compat_ioctl for now because sr_block_ioctl never
-	 * seems to pass arbitary ioctls down to host drivers.
+	 * seems to pass arbitrary ioctls down to host drivers.
 	 */
 };